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VECTASTAIN Elite ABC-Peroxidase Kit

RRID:AB_2336819

β3 -adrenoceptor stimulation of perivascular adipocytes leads to increased fat cell-derived nitric oxide and vascular relaxation in small arteries.

  • Bussey CE
  • Br. J. Pharmacol.
  • 2018 Jul 6

Literature context:


Abstract:

BACKGROUND AND PURPOSE: In response to norepinephrine healthy perivascular adipose tissue (PVAT) exerts an anticontractile effect on adjacent small arterial tissue. Organ bath solution transfer experiments have demonstrated the release of PVAT-derived relaxing factors that mediate this function. The present studies were designed to investigate the mechanism responsible for the norepinephrine-induced PVAT anticontractile effect. EXPERIMENTAL APPROACH: In vitro rat small arterial contractile function was assessed using wire myography in the presence and absence of PVAT and the effects of sympathomimetic stimulation on the PVAT environment explored using Western blotting and assays of organ bath buffer. KEY RESULTS: PVAT elicited an anticontractile effect in response to norepinephrine but not phenylephrine stimulation. In arteries surrounded by intact PVAT, the β3 -adrenoceptor agonist, CL-316,243 reduced the vasoconstrictor effect of phenylephrine but not norepinephrine. Kv 7 channel inhibition using XE 991 reversed the norepinephrine-induced anticontractile effect in exogenously applied PVAT studies. Adrenergic stimulation of PVAT with norepinephrine and CL-316,243, but not phenylephrine was associated with increased adipocyte-derived nitric oxide production and the contractile response to norepinephrine was augmented following incubation of exogenous PVAT with L-NMMA. PVAT from eNOS-/- mice had no anticontractile effect. Assays of adipocyte cAMP demonstrated an increase with norepinephrine stimulation implicating Gαs signalling in this process. CONCLUSIONS AND IMPLICATIONS: We have shown that adipocyte-located β3 -adrenoceptor stimulation leads to activation of Gαs signaling pathways with increased cAMP and the release of adipocyte-derived nitric oxide. This process is dependent upon Kv 7 channel function. We conclude that adipocyte-derived nitric oxide plays a central role in anticontractile activity when rodent PVAT is stimulated by norepinephrine.

Funding information:
  • NCRR NIH HHS - R24 RR017718(United States)

G-Protein-Coupled Receptor Gpr17 Expression in Two Multiple Sclerosis Remyelination Models.

  • Nyamoya S
  • Mol. Neurobiol.
  • 2018 Jun 5

Literature context:


Abstract:

In multiple sclerosis patients, demyelination is prominent in both the white and gray matter. Chronic clinical deficits are known to result from acute or chronic injury to the myelin sheath and inadequate remyelination. The underlying molecular mechanisms of remyelination and its failure remain currently unclear. Recent studies have recognized G protein-coupled receptor 17 (GPR17) as an important regulator of oligodendrocyte development and remyelination. So far, the relevance of GPR17 for myelin repair was mainly tested in remyelinating white matter lesions. The relevance of GPR17 for gray matter remyelination as well as remyelination of chronic white matter lesions was not addressed so far. Here, we provide a detailed characterization of GPR17 expression during experimental de- and remyelination. Experimental lesions with robust and limited endogenous remyelination capacity were established by either acute or chronic cuprizone-induced demyelination. Furthermore, remyelinating lesions were induced by the focal injection of lysophosphatidylcholine (LPC) into the corpus callosum. GPR17 expression was analyzed by complementary techniques including immunohistochemistry, in situ hybridization, and real-time PCR. In control animals, GPR17+ cells were evenly distributed in the corpus callosum and cortex and displayed a highly ramified morphology. Virtually all GPR17+ cells also expressed the oligodendrocyte-specific transcription factor OLIG2. After acute cuprizone-induced demyelination, robust endogenous remyelination was evident in the white matter corpus callosum but not in the gray matter cortex. Endogenous callosal remyelination was paralleled by a robust induction of GPR17 expression which was absent in the gray matter cortex. Higher numbers of GPR17+ cells were as well observed after LPC-induced focal white matter demyelination. In contrast, densities of GPR17+ cells were comparable to control animals after chronic cuprizone-induced demyelination indicating quiescence of this cell population. Our findings demonstrate that GPR17 expression induction correlates with acute demyelination and sufficient endogenous remyelination. This strengthens the view that manipulation of this receptor might be a therapeutic opportunity to support endogenous remyelination.

Funding information:
  • Deutsche Forschungsgemeinschaft - KI 1469/8-1()
  • NIGMS NIH HHS - R01 GM085490-03(United States)

Fetal Neuropathology in Zika Virus-Infected Pregnant Female Rhesus Monkeys.

  • Martinot AJ
  • Cell
  • 2018 May 17

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Abstract:

The development of interventions to prevent congenital Zika syndrome (CZS) has been limited by the lack of an established nonhuman primate model. Here we show that infection of female rhesus monkeys early in pregnancy with Zika virus (ZIKV) recapitulates many features of CZS in humans. We infected 9 pregnant monkeys with ZIKV, 6 early in pregnancy (weeks 6-7 of gestation) and 3 later in pregnancy (weeks 12-14 of gestation), and compared findings with uninfected controls. 100% (6 of 6) of monkeys infected early in pregnancy exhibited prolonged maternal viremia and fetal neuropathology, including fetal loss, smaller brain size, and histopathologic brain lesions, including microcalcifications, hemorrhage, necrosis, vasculitis, gliosis, and apoptosis of neuroprogenitor cells. High-resolution MRI demonstrated concordant lesions indicative of deep gray matter injury. We also observed spinal, ocular, and neuromuscular pathology. Our data show that vascular compromise and neuroprogenitor cell dysfunction are hallmarks of CZS pathogenesis, suggesting novel strategies to prevent and to treat this disease.

Funding information:
  • NIAID NIH HHS - 2R01 AI056153(United States)
  • NIAID NIH HHS - U19 AI096040()
  • NIAID NIH HHS - U19 AI128751()
  • NIAID NIH HHS - UM1 AI124377()

Serotonergic Signaling Controls Input-Specific Synaptic Plasticity at Striatal Circuits.

  • Cavaccini A
  • Neuron
  • 2018 May 16

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Abstract:

Monoaminergic modulation of cortical and thalamic inputs to the dorsal striatum (DS) is crucial for reward-based learning and action control. While dopamine has been extensively investigated in this context, the synaptic effects of serotonin (5-HT) have been largely unexplored. Here, we investigated how serotonergic signaling affects associative plasticity at glutamatergic synapses on the striatal projection neurons of the direct pathway (dSPNs). Combining chemogenetic and optogenetic approaches reveals that impeding serotonergic signaling preferentially gates spike-timing-dependent long-term depression (t-LTD) at thalamostriatal synapses. This t-LTD requires dampened activity of the 5-HT4 receptor subtype, which we demonstrate controls dendritic Ca2+ signals by regulating BK channel activity, and which preferentially localizes at the dendritic shaft. The synaptic effects of 5-HT signaling at thalamostriatal inputs provide insights into how changes in serotonergic levels associated with behavioral states or pathology affect striatal-dependent processes.

Funding information:
  • Wellcome Trust - (United Kingdom)

A Subpopulation of Striatal Neurons Mediates Levodopa-Induced Dyskinesia.

  • Girasole AE
  • Neuron
  • 2018 Feb 21

Literature context:


Abstract:

Parkinson's disease is characterized by the progressive loss of midbrain dopamine neurons. Dopamine replacement therapy with levodopa alleviates parkinsonian motor symptoms but is complicated by the development of involuntary movements, termed levodopa-induced dyskinesia (LID). Aberrant activity in the striatum has been hypothesized to cause LID. Here, to establish a direct link between striatal activity and dyskinesia, we combine optogenetics and a method to manipulate dyskinesia-associated neurons, targeted recombination in active populations (TRAP). We find that TRAPed cells are a stable subset of sensorimotor striatal neurons, predominantly from the direct pathway, and that reactivation of TRAPed striatal neurons causes dyskinesia in the absence of levodopa. Inhibition of TRAPed cells, but not a nonspecific subset of direct pathway neurons, ameliorates LID. These results establish that a distinct subset of striatal neurons is causally involved in LID and indicate that successful therapeutic strategies for treating LID may require targeting functionally selective neuronal subtypes.

Activity in the Ventral Medial Prefrontal Cortex Is Necessary for the Therapeutic Effects of Extinction in Rats.

  • Fucich EA
  • J. Neurosci.
  • 2018 Feb 7

Literature context:


Abstract:

Poor response and high relapse rates remain problematic in the treatment of stress-related psychiatric disorders such as depression and post-traumatic stress disorder. Although mechanisms of pharmacotherapies are intensely studied, little is known about mechanisms of behavioral therapy that could inform improved treatments. We have previously demonstrated the therapeutic effects of extinction learning as a behavioral intervention modeling exposure therapy in rats. In the present study, we tested the hypothesis that activity in the ventral medial prefrontal cortex (vmPFC) during extinction is necessary for its therapeutic effects. The inhibitory Gi-coupled designer receptor exclusively activated by designer drug CaMKIIα-hM4Di was expressed in vmPFC before administering chronic unpredictable stress (CUS). vmPFC projection neurons were then inhibited during extinction treatment by administering clozapine-N-oxide. Coping behavior and cognitive flexibility were assessed 24 h later on the shock-probe defensive burying test and attentional set-shifting test, respectively. Replicating previous results, extinction reversed the CUS-induced deficits in coping behavior and cognitive flexibility. Inhibiting vmPFC during extinction blocked these therapeutic effects. Further, increasing vmPFC activity with the excitatory Gq-coupled designer receptor exclusively activated by designer drug hM3Dq 24 h before testing was sufficient to reverse the CUS-induced deficits. CUS reduced mPFC responsivity, assessed by measuring afferent-evoked field potentials in the mPFC, and this reduction was reversed by extinction treatment 24 h before testing. These results demonstrate the necessity of vmPFC activity in the therapeutic effects of extinction as a model of exposure therapy, and suggest that increased vmPFC activity induced by extinction is sufficient to produce lasting plastic changes that underlie its beneficial effects.SIGNIFICANCE STATEMENT Stress-related psychiatric disorders remain poorly treated. Psychotherapies can be effective, but their mechanisms remain unknown, hindering progress toward improved treatment. We used a rat model of behavioral therapy to identify potential targets for enhancing treatment. Fear extinction as a therapeutic behavioral intervention reversed stress-induced cognitive dysfunction and passive coping in rats, modeling components of stress-related psychiatric disease. Extinction also reversed stress-induced attenuation of mPFC responsivity. The therapeutic effects were prevented by blocking activity of glutamatergic neurons in the mPFC during extinction, and were mimicked by inducing activity in lieu of extinction. Thus, activity and plasticity in the mPFC underlie the beneficial effects of extinction on cognitive flexibility and coping behavior compromised by stress, and could be targets to enhance behavioral therapy.

Funding information:
  • NCI NIH HHS - R01-CA118750(United States)

Radial Glial Fibers Promote Neuronal Migration and Functional Recovery after Neonatal Brain Injury.

  • Jinnou H
  • Cell Stem Cell
  • 2018 Jan 4

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Abstract:

Radial glia (RG) are embryonic neural stem cells (NSCs) that produce neuroblasts and provide fibers that act as a scaffold for neuroblast migration during embryonic development. Although they normally disappear soon after birth, here we found that RG fibers can persist in injured neonatal mouse brains and act as a scaffold for postnatal ventricular-subventricular zone (V-SVZ)-derived neuroblasts that migrate to the lesion site. This injury-induced maintenance of RG fibers has a limited time window during post-natal development and promotes directional saltatory movement of neuroblasts via N-cadherin-mediated cell-cell contacts that promote RhoA activation. Transplanting an N-cadherin-containing scaffold into injured neonatal brains likewise promotes migration and maturation of V-SVZ-derived neuroblasts, leading to functional improvements in impaired gait behaviors. Together these results suggest that RG fibers enable postnatal V-SVZ-derived neuroblasts to migrate toward sites of injury, thereby enhancing neuronal regeneration and functional recovery from neonatal brain injuries.

Funding information:
  • NIDDK NIH HHS - R01 DK082659(United States)

Neuronal Glutamate Transporters Control Dopaminergic Signaling and Compulsive Behaviors.

  • Bellini S
  • J. Neurosci.
  • 2018 Jan 24

Literature context:


Abstract:

There is an ongoing debate on the contribution of the neuronal glutamate transporter EAAC1 to the onset of compulsive behaviors. Here, we used behavioral, electrophysiological, molecular, and viral approaches in male and female mice to identify the molecular and cellular mechanisms by which EAAC1 controls the execution of repeated motor behaviors. Our findings show that, in the striatum, a brain region implicated with movement execution, EAAC1 limits group I metabotropic glutamate receptor (mGluRI) activation, facilitates D1 dopamine receptor (D1R) expression, and ensures long-term synaptic plasticity. Blocking mGluRI in slices from mice lacking EAAC1 restores D1R expression and synaptic plasticity. Conversely, activation of intracellular signaling pathways coupled to mGluRI in D1R-containing striatal neurons of mice expressing EAAC1 leads to reduced D1R protein level and increased stereotyped movement execution. These findings identify new molecular mechanisms by which EAAC1 can shape glutamatergic and dopaminergic signals and control repeated movement execution.SIGNIFICANCE STATEMENT Genetic studies implicate Slc1a1, a gene encoding the neuronal glutamate transporter EAAC1, with obsessive-compulsive disorder (OCD). EAAC1 is abundantly expressed in the striatum, a brain region that is hyperactive in OCD. What remains unknown is how EAAC1 shapes synaptic function in the striatum. Our findings show that EAAC1 limits activation of metabotropic glutamate receptors (mGluRIs) in the striatum and, by doing so, promotes D1 dopamine receptor (D1R) expression. Targeted activation of signaling cascades coupled to mGluRIs in mice expressing EAAC1 reduces D1R expression and triggers repeated motor behaviors. These findings provide new information on the molecular basis of OCD and suggest new avenues for its treatment.

Funding information:
  • NINDS NIH HHS - R01 NS032273(United States)

Injured adult motor and sensory axons regenerate into appropriate organotypic domains of neural progenitor grafts.

  • Dulin JN
  • Nat Commun
  • 2018 Jan 8

Literature context:


Abstract:

Neural progenitor cell (NPC) transplantation has high therapeutic potential in neurological disorders. Functional restoration may depend on the formation of reciprocal connections between host and graft. While it has been reported that axons extending out of neural grafts in the brain form contacts onto phenotypically appropriate host target regions, it is not known whether adult, injured host axons regenerating into NPC grafts also form appropriate connections. We report that spinal cord NPCs grafted into the injured adult rat spinal cord self-assemble organotypic, dorsal horn-like domains. These clusters are extensively innervated by regenerating adult host sensory axons and are avoided by corticospinal axons. Moreover, host axon regeneration into grafts increases significantly after enrichment with appropriate neuronal targets. Together, these findings demonstrate that injured adult axons retain the ability to recognize appropriate targets and avoid inappropriate targets within neural progenitor grafts, suggesting that restoration of complex circuitry after SCI may be achievable.

Funding information:
  • NIDCD NIH HHS - R21DC005846(United States)
  • NINDS NIH HHS - R01 NS042291()
  • NINDS NIH HHS - R56 NS042291()

Removal of prolyl oligopeptidase reduces alpha-synuclein toxicity in cells and in vivo.

  • Svarcbahs R
  • Sci Rep
  • 2018 Jan 24

Literature context:


Abstract:

Prolyl oligopeptidase (PREP) inhibition by small-molecule inhibitors can reduce alpha-synuclein (aSyn) aggregation, a key player in Parkinson's disease pathology. However, the significance of PREP protein for aSyn aggregation and toxicity is not known. We studied this in vivo by using PREP knock-out mice with viral vector injections of aSyn and PREP. Animal behavior was studied by locomotor activity and cylinder tests, microdialysis and HPLC were used to analyze dopamine levels, and different aSyn forms and loss of dopaminergic neurons were studied by immunostainings. Additionally, PREP knock-out cells were used to characterize the impact of PREP and aSyn on autophagy, proteasomal system and aSyn secretion. PREP knock-out animals were nonresponsive to aSyn-induced unilateral toxicity but combination of PREP and aSyn injections increased aSyn toxicity. Phosphorylated p129, proteinase K resistant aSyn levels and tyrosine hydroxylase positive cells were decreased in aSyn and PREP injected knock-out animals. These changes were accompanied by altered dopamine metabolite levels. PREP knock-out cells showed reduced response to aSyn, while cells were restored to wild-type cell levels after PREP overexpression. Taken together, our data suggests that PREP can enhance aSyn toxicity in vivo.

Funding information:
  • National Cancer Institute - CA163820A1(United States)

Neuronal PTEN deletion in adult cortical neurons triggers progressive growth of cell bodies, dendrites, and axons.

  • Gallent EA
  • Exp. Neurol.
  • 2018 Jan 18

Literature context:


Abstract:

Deletion of the phosphatase and tensin (PTEN) gene in neonatal mice leads to enlargement of the cell bodies of cortical motoneurons (CMNs) in adulthood (Gutilla et al., 2016). Here, we assessed whether PTEN deletion in adult mice would trigger growth of mature neurons. PTEN was deleted by injecting AAV-Cre into the sensorimotor cortex of adult transgenic mice with a lox-P flanked exon 5 of the PTEN gene and Cre-dependent reporter gene tdTomato. PTEN-deleted CMN's identified by tdT expression and retrograde labeling with fluorogold (FG) were significantly enlarged four months following PTEN deletion, and continued to increase in size through the latest time intervals examined (12-15 months post-deletion). Sholl analyses of tdT-positive pyramidal neurons revealed increases in dendritic branches at 6 months following adult PTEN deletion, and greater increases at 12 months. 12 months after adult PTEN deletion, axons in the medullary pyramids were significantly larger and G-ratios were higher. Mice with PTEN deletion exhibited no overt neurological symptoms and no seizures. Assessment of motor function on the rotarod and cylinder test revealed slight impairment of coordination with unilateral deletion; however, mice with bilateral PTEN deletion in the motor cortex performed better than controls on the rotarod at 8 and 10 months post-deletion. Our findings demonstrate that robust neuronal growth can be induced in fully mature cortical neurons long after the developmental period has ended and that this continuous growth occurs without obvious functional impairments.

Funding information:
  • NIGMS NIH HHS - R01 GM049650(United States)

Identification of a conserved gene signature associated with an exacerbated inflammatory environment in the hippocampus of aging rats.

  • Pardo J
  • Hippocampus
  • 2018 Jan 10

Literature context:


Abstract:

There have been a few descriptive studies in aged rodents about transcriptome changes in the hippocampus, most of them in males. Here, we assessed the age changes in spatial memory performance and hippocampal morphology in female rats and compared those changes with changes in the hippocampal transcriptome. Old rats displayed significant deficits in spatial memory. In both age groups, hole exploration frequency showed a clear peak at hole 0 (escape hole), but the amplitude of the peak was significantly higher in the young than in the old animals. In the hippocampus, there was a dramatic reduction in neurogenesis, whereas reactive microglial infiltrates revealed an inflammatory hippocampal state in the senile rats. Hippocampal RNA-sequencing showed that 210 genes are differentially expressed in the senile rats, most of them being downregulated. Our RNA-Seq data showed that various genes involved in the immune response, including TYROBP, CD11b, C3, CD18, CD4, and CD74, are overexpressed in the hippocampus of aged female rats. Enrichment analysis showed that the pathways overrepresented in the senile rats matched those of an exacerbated inflammatory environment, reinforcing our morphologic findings. After correlating our results with public data of human and mouse hippocampal gene expression, we found an 11-gene signature of overexpressed genes related to inflammatory processes that was conserved across species. We conclude that age-related hippocampal deficits in female rats share commonalities between human and rodents. Interestingly, the 11-gene signature that we identified may represent a cluster of immune and regulatory genes that are deregulated in the hippocampus and possibly other brain regions during aging as well as in some neurodegenerative diseases and low-grade brain tumors. Our study further supports neuroinflammation as a promising target to treat cognitive dysfunction in old individuals and some brain tumors. © 2017 Wiley Periodicals, Inc.

Comparative investigation of neuronal nitric oxide synthase immunoreactivity in rat and human claustrum.

  • Landzhov B
  • J. Chem. Neuroanat.
  • 2017 Dec 19

Literature context:


Abstract:

We compared the distribution, density and morphological characteristics of nitric oxide synthase-immunoreactive (NOS-ir) neurons in the rat and human claustrum. These neurons were categorized by diameter into three main types: large, medium and small. In the human claustrum, large neurons ranged from 26 to 40μm in diameter, medium neurons from 20 to 25μm and small neurons from 13 to 19μm. In the rat claustrum, large neurons ranged from 19 to 23μm in diameter, medium neurons from 15 to 18μm and small neurons from 10 to 14μm. The cell bodies of large and medium neurons varied broadly in shape - multipolar, elliptical, bipolar and irregular, consistent with a projection neuron phenotype. The small neurons were most seen as being oval or elliptical in shape, resembling an interneuron phenotype. Based on a quantitative comparison of their dendritic characteristics, the NOS-ir neurons of humans and rats displayed a statistically significant difference.

Distinct projection targets define subpopulations of mouse brainstem vagal neurons that express the autism-associated MET receptor tyrosine kinase.

  • Kamitakahara A
  • J. Comp. Neurol.
  • 2017 Dec 15

Literature context:


Abstract:

Detailed anatomical tracing and mapping of the viscerotopic organization of the vagal motor nuclei has provided insight into autonomic function in health and disease. To further define specific cellular identities, we paired information based on visceral connectivity with a cell-type specific marker of a subpopulation of neurons in the dorsal motor nucleus of the vagus (DMV) and nucleus ambiguus (nAmb) that express the autism-associated MET receptor tyrosine kinase. As gastrointestinal disturbances are common in children with autism spectrum disorder (ASD), we sought to define the relationship between MET-expressing (MET+) neurons in the DMV and nAmb, and the gastrointestinal tract. Using wholemount tissue staining and clearing, or retrograde tracing in a METEGFP transgenic mouse, we identify three novel subpopulations of EGFP+ vagal brainstem neurons: (a) EGFP+ neurons in the nAmb projecting to the esophagus or laryngeal muscles, (b) EGFP+ neurons in the medial DMV projecting to the stomach, and (b) EGFP+ neurons in the lateral DMV projecting to the cecum and/or proximal colon. Expression of the MET ligand, hepatocyte growth factor (HGF), by tissues innervated by vagal motor neurons during fetal development reveal potential sites of HGF-MET interaction. Furthermore, similar cellular expression patterns of MET in the brainstem of both the mouse and nonhuman primate suggests that MET expression at these sites is evolutionarily conserved. Together, the data suggest that MET+ neurons in the brainstem vagal motor nuclei are anatomically positioned to regulate distinct portions of the gastrointestinal tract, with implications for the pathophysiology of gastrointestinal comorbidities of ASD.

Distribution and female reproductive state differences in orexigenic and anorexigenic neurons in the brain of the mouth brooding African cichlid fish, Astatotilapia burtoni.

  • Porter DT
  • J. Comp. Neurol.
  • 2017 Oct 1

Literature context:


Abstract:

Integration of reproduction and metabolism is necessary for species survival. While the neural circuits controlling energy homeostasis are well-characterized, the signals controlling the relay of nutritional information to the reproductive axis are less understood. The cichlid fish Astatotilapia burtoni is ideal for studying the neural regulation of feeding and reproduction because females cycle between a feeding gravid state and a period of forced starvation while they brood developing young inside their mouths. To test the hypothesis that candidate neuropeptide-containing neurons known to be involved in feeding and energy homeostasis in mammals show conserved distribution patterns, we performed immunohistochemistry and in situ hybridization to localize appetite-stimulating (neuropeptide Y, NPY; agouti-related protein, AGRP) and appetite-inhibiting (cocaine and amphetamine-regulated transcript, CART; pro-opiomelanocortin, pomc1a) neurons in the brain. NPY, AGRP, CART, and pomc1a somata showed distribution patterns similar to other teleosts, which included localization to the lateral tuberal nucleus (NLT), the putative homolog of the mammalian arcuate nucleus. Gravid females also had larger NPY and AGRP neurons in the NLT compared to brooding females, but brooding females had larger pomc1a neurons compared to gravid females. Hypothalamic agrp mRNA levels were also higher in gravid compared to brooding females. Thus, larger appetite-stimulating neurons (NPY, AGRP) likely promote feeding while females are gravid, while larger pomc1a neurons may act as a signal to inhibit food intake during mouth brooding. Collectively, our data suggest a potential role for NPY, AGRP, POMC, and CART in regulating energetic status in A. burtoni females during varying metabolic and reproductive demands.

Glycinergic Input to the Mouse Basal Forebrain Cholinergic Neurons.

  • Bardóczi Z
  • J. Neurosci.
  • 2017 Sep 27

Literature context:


Abstract:

The basal forebrain (BF) receives afferents from brainstem ascending pathways, which has been implicated first by Moruzzi and Magoun (1949) to induce forebrain activation and cortical arousal/waking behavior; however, it is very little known about how brainstem inhibitory inputs affect cholinergic functions. In the current study, glycine, a major inhibitory neurotransmitter of brainstem neurons, and gliotransmitter of local glial cells, was tested for potential interaction with BF cholinergic (BFC) neurons in male mice. In the BF, glycine receptor α subunit-immunoreactive (IR) sites were localized in choline acetyltransferase (ChAT)-IR neurons. The effect of glycine on BFC neurons was demonstrated by bicuculline-resistant, strychnine-sensitive spontaneous IPSCs (sIPSCs; 0.81 ± 0.25 × 10-1 Hz) recorded in whole-cell conditions. Potential neuronal as well as glial sources of glycine were indicated in the extracellular space of cholinergic neurons by glycine transporter type 1 (GLYT1)- and GLYT2-IR processes found in apposition to ChAT-IR cells. Ultrastructural analyses identified synapses of GLYT2-positive axon terminals on ChAT-IR neurons, as well as GLYT1-positive astroglial processes, which were localized in the vicinity of synapses of ChAT-IR neurons. The brainstem raphe magnus was determined to be a major source of glycinergic axons traced retrogradely from the BF. Our results indicate a direct effect of glycine on BFC neurons. Furthermore, the presence of high levels of plasma membrane glycine transporters in the vicinity of cholinergic neurons suggests a tight control of extracellular glycine in the BF.SIGNIFICANCE STATEMENT Basal forebrain cholinergic (BFC) neurons receive various activating inputs from specific brainstem areas and channel this information to the cortex via multiple projections. So far, very little is known about inhibitory brainstem afferents to the BF. The current study established glycine as a major regulator of BFC neurons by (1) identifying glycinergic neurons in the brainstem projecting to the BF, (2) showing glycine receptor α subunit-immunoreactive (IR) sites in choline acetyltransferase (ChAT)-IR neurons, (3) demonstrating glycine transporter type 2 (GLYT2)-positive axon terminals synapsing on ChAT-IR neurons, and (4) localizing GLYT1-positive astroglial processes in the vicinity of synapses of ChAT-IR neurons. The effect of glycine on BFC neurons was demonstrated by bicuculline-resistant, strychnine-sensitive spontaneous IPSCs recorded in whole-cell conditions.

Parallel Inhibitory and Excitatory Trigemino-Facial Feedback Circuitry for Reflexive Vibrissa Movement.

  • Bellavance MA
  • Neuron
  • 2017 Aug 2

Literature context:


Abstract:

Animals employ active touch to optimize the acuity of their tactile sensors. Prior experimental results and models lead to the hypothesis that sensory inputs are used in a recurrent manner to tune the position of the sensors. A combination of electrophysiology, intersectional genetic viral labeling and manipulation, and classical tracing allowed us to identify second-order sensorimotor loops that control vibrissa movements by rodents. Facial motoneurons that drive intrinsic muscles to protract the vibrissae receive a short latency inhibitory input, followed by synaptic excitation, from neurons located in the oralis division of the trigeminal sensory complex. In contrast, motoneurons that retract the mystacial pad and indirectly retract the vibrissae receive only excitatory input from interpolaris cells that further project to the thalamus. Silencing this feedback alters retraction. The observed pull-push circuit at the lowest-level sensorimotor loop provides a mechanism for the rapid modulation of vibrissa touch during exploration of peri-personal space.

Differential neuronal and glial expression of nuclear factor I proteins in the cerebral cortex of adult mice.

  • Chen KS
  • J. Comp. Neurol.
  • 2017 Aug 1

Literature context:


Abstract:

The nuclear factor I (NFI) family of transcription factors plays an important role in the development of the cerebral cortex in humans and mice. Disruption of nuclear factor IA (NFIA), nuclear factor IB (NFIB), or nuclear factor IX (NFIX) results in abnormal development of the corpus callosum, lateral ventricles, and hippocampus. However, the expression or function of these genes has not been examined in detail in the adult brain, and the cell type-specific expression of NFIA, NFIB, and NFIX is currently unknown. Here, we demonstrate that the expression of each NFI protein shows a distinct laminar pattern in the adult mouse neocortex and that their cell type-specific expression differs depending on the family member. NFIA expression was more frequently observed in astrocytes and oligodendroglia, whereas NFIB expression was predominantly localized to astrocytes and neurons. NFIX expression was most commonly observed in neurons. The NFI proteins were equally distributed within microglia, and the ependymal cells lining the ventricles of the brain expressed all three proteins. In the hippocampus, the NFI proteins were expressed during all stages of neural stem cell differentiation in the dentate gyrus, with higher expression intensity in neuroblast cells as compared to quiescent stem cells and mature granule neurons. These findings suggest that the NFI proteins may play distinct roles in cell lineage specification or maintenance, and establish the basis for further investigation of their function in the adult brain and their emerging role in disease.

The DYT6 Dystonia Protein THAP1 Regulates Myelination within the Oligodendrocyte Lineage.

  • Yellajoshyula D
  • Dev. Cell
  • 2017 Jul 10

Literature context:


Abstract:

The childhood-onset motor disorder DYT6 dystonia is caused by loss-of-function mutations in the transcription factor THAP1, but the neurodevelopmental processes in which THAP1 participates are unknown. We find that THAP1 is essential for the timing of myelination initiation during CNS maturation. Conditional deletion of THAP1 in the CNS retards maturation of the oligodendrocyte (OL) lineage, delaying myelination and causing persistent motor deficits. The CNS myelination defect results from a cell-autonomous requirement for THAP1 in the OL lineage and is recapitulated in developmental assays performed on OL progenitor cells purified from Thap1 null mice. Loss of THAP1 function disrupts a core set of OL maturation genes and reduces the DNA occupancy of YY1, a transcription factor required for OL maturation. These studies establish a role for THAP1 transcriptional regulation at the inception of myelination and implicate abnormal timing of myelination in the pathogenesis of childhood-onset dystonia.

5HTR3A-driven GFP labels immature olfactory sensory neurons.

  • Finger TE
  • J. Comp. Neurol.
  • 2017 May 1

Literature context:


Abstract:

The ionotropic serotonin receptor, 5-HT3 , is expressed by many developing neurons within the central nervous system. Since the olfactory epithelium continues to generate new olfactory sensory neurons (OSNs) throughout life, we investigated the possibility that 5-HT3 is expressed in the adult epithelium. Using a transgenic mouse in which the promoter for the 5-HT3a subunit drives expression of green fluorescent protein (GFP), we assessed the expression of this marker in the olfactory epithelium of adult mice. Both the native 5-HT3a mRNA and GFP are expressed within globose basal cells of the olfactory and vomeronasal epithelium in adult mice. Whereas the 5-HT3a mRNA disappears relatively quickly after final cell division, the GFP label persists for about 5 days, thereby labeling immature OSNs in both the main olfactory system and vomeronasal organ. The GFP-labeled cells include both proliferative globose basal cells as well as immature OSNs exhibiting the hallmarks of ongoing differentiation including GAP43, PGP9.5, but the absence of olfactory marker protein. Some of the GFP-labeled OSNs show characteristics of more mature yet still developing OSNs including the presence of cilia extending from the apical knob and expression of NaV1.5, a component of the transduction cascade. These findings suggest that 5-HT3a is indicative of a proliferative or developmental state, regardless of age, and that the 5-HT3A GFP mice may prove useful for future studies of neurogenesis in the olfactory epithelium. J. Comp. Neurol. 525:1743-1755, 2017. © 2016 Wiley Periodicals, Inc.

Mutant Huntingtin Disrupts the Nuclear Pore Complex.

  • Grima JC
  • Neuron
  • 2017 Apr 5

Literature context:


Abstract:

Huntington's disease (HD) is caused by an expanded CAG repeat in the Huntingtin (HTT) gene. The mechanism(s) by which mutant HTT (mHTT) causes disease is unclear. Nucleocytoplasmic transport, the trafficking of macromolecules between the nucleus and cytoplasm, is tightly regulated by nuclear pore complexes (NPCs) made up of nucleoporins (NUPs). Previous studies offered clues that mHTT may disrupt nucleocytoplasmic transport and a mutation of an NUP can cause HD-like pathology. Therefore, we evaluated the NPC and nucleocytoplasmic transport in multiple models of HD, including mouse and fly models, neurons transfected with mHTT, HD iPSC-derived neurons, and human HD brain regions. These studies revealed severe mislocalization and aggregation of NUPs and defective nucleocytoplasmic transport. HD repeat-associated non-ATG (RAN) translation proteins also disrupted nucleocytoplasmic transport. Additionally, overexpression of NUPs and treatment with drugs that prevent aberrant NUP biology also mitigated this transport defect and neurotoxicity, providing future novel therapy targets.

Funding information:
  • NINDS NIH HHS - R01 NS082338()
  • NINDS NIH HHS - R01 NS085207()
  • NINDS NIH HHS - R01 NS090390()
  • NINDS NIH HHS - R01 NS094239()
  • NINDS NIH HHS - U54 NS091046()

DNA-PKcs, ATM, and ATR Interplay Maintains Genome Integrity during Neurogenesis.

  • Enriquez-Rios V
  • J. Neurosci.
  • 2017 Jan 25

Literature context:


Abstract:

The DNA damage response (DDR) orchestrates a network of cellular processes that integrates cell-cycle control and DNA repair or apoptosis, which serves to maintain genome stability. DNA-PKcs (the catalytic subunit of the DNA-dependent kinase, encoded by PRKDC), ATM (ataxia telangiectasia, mutated), and ATR (ATM and Rad3-related) are related PI3K-like protein kinases and central regulators of the DDR. Defects in these kinases have been linked to neurodegenerative or neurodevelopmental syndromes. In all cases, the key neuroprotective function of these kinases is uncertain. It also remains unclear how interactions between the three DNA damage-responsive kinases coordinate genome stability, particularly in a physiological context. Here, we used a genetic approach to identify the neural function of DNA-PKcs and the interplay between ATM and ATR during neurogenesis. We found that DNA-PKcs loss in the mouse sensitized neuronal progenitors to apoptosis after ionizing radiation because of excessive DNA damage. DNA-PKcs was also required to prevent endogenous DNA damage accumulation throughout the adult brain. In contrast, ATR coordinated the DDR during neurogenesis to direct apoptosis in cycling neural progenitors, whereas ATM regulated apoptosis in both proliferative and noncycling cells. We also found that ATR controls a DNA damage-induced G2/M checkpoint in cortical progenitors, independent of ATM and DNA-PKcs. These nonoverlapping roles were further confirmed via sustained murine embryonic or cortical development after all three kinases were simultaneously inactivated. Thus, our results illustrate how DNA-PKcs, ATM, and ATR have unique and essential roles during the DDR, collectively ensuring comprehensive genome maintenance in the nervous system. SIGNIFICANCE STATEMENT: The DNA damage response (DDR) is essential for prevention of a broad spectrum of different human neurologic diseases. However, a detailed understanding of the DDR at a physiological level is lacking. In contrast to many in vitro cellular studies, here we demonstrate independent biological roles for the DDR kinases DNA-PKcs, ATM, and ATR during neurogenesis. We show that DNA-PKcs is central to DNA repair in nonproliferating cells, and restricts DNA damage accumulation, whereas ATR controls damage-induced G2 checkpoint control and apoptosis in proliferating cells. Conversely, ATM is critical for controlling apoptosis in immature noncycling neural cells after DNA damage. These data demonstrate functionally distinct, but cooperative, roles for each kinase in preserving genome stability in the nervous system.

Funding information:
  • NCI NIH HHS - P01 CA096832()
  • NCI NIH HHS - P30 CA021765()
  • NIA NIH HHS - R01 AG027376()
  • NINDS NIH HHS - R01 NS037956()
  • NINDS NIH HHS - R56 NS037956()

Inhibition of Prolyl Oligopeptidase Restores Spontaneous Motor Behavior in the α-Synuclein Virus Vector-Based Parkinson's Disease Mouse Model by Decreasing α-Synuclein Oligomeric Species in Mouse Brain.

  • Svarcbahs R
  • J. Neurosci.
  • 2016 Dec 7

Literature context:


Abstract:

Decreased clearance of α-synuclein (aSyn) and aSyn protein misfolding and aggregation are seen as major factors in the pathogenesis of Parkinson's disease (PD) and other synucleinopathies that leads to disruption in neuronal function and eventually to cell death. Prolyl oligopeptidase (PREP) can accelerate the aSyn aggregation process, while inhibition of PREP by a small molecule inhibitor decreases aSyn oligomer formation and enhances its clearance via autophagy in different aSyn overexpressing cell types and in transgenic PD animal models. In this study, we investigated the impact of chronic PREP inhibition by a small molecule inhibitor, 4-phenylbutanoyl-l-prolyl-2(S)-cyanopyrrolidine (KYP-2047), on aSyn oligomerization, clearance, and underlying spontaneous motor behavior in a virus vector-based aSyn overexpression mouse model 4 weeks after aSyn microinjections and after the onset of symptomatic forepaw bias. Following 4 weeks of PREP inhibition, we saw an improved spontaneous forelimb use in mice that correlated with a decreased immunoreactivity against oligomer-specific forms of aSyn. Additionally, KYP-2047 had a trend to enhance dopaminergic systems activity. Our results suggest that PREP inhibition exhibits a beneficial effect on the aSyn clearance and aggregation in a virus mediated aSyn overexpression PD mouse model and that PREP inhibitors could be a novel therapeutic strategy for synucleinopathies. SIGNIFICANCE STATEMENT: Alpha-synuclein (aSyn) has been implicated in Parkinson's disease, with aSyn aggregates believed to exert toxic effects on neurons, while prolyl oligopeptidase (PREP) has been shown to interact with aSyn both in cells and cell free conditions, thus enhancing its aggregation. We demonstrate the possibility to abolish motor imbalance caused by aSyn viral vector injection with chronic 4 week PREP inhibition by a potent small-molecule PREP inhibitor, 4-phenylbutanoyl-l-prolyl-2(S)-cyanopyrrolidine (KYP-2047). Treatment was initiated postsymptomatically, 4 weeks after aSyn injection. KYP-2047-treated animals had a significantly decreased amount of oligomeric aSyn particles and improved dopamine system activity compared to control animals. To our knowledge, this is the first time viral overexpression of aSyn has been countered and movement impairments abolished after their onset.

Ventral Tegmental Area Dopamine Cell Activation during Male Rat Sexual Behavior Regulates Neuroplasticity and d-Amphetamine Cross-Sensitization following Sex Abstinence.

  • Beloate LN
  • J. Neurosci.
  • 2016 Sep 21

Literature context:


Abstract:

Experience with sexual behavior causes cross-sensitization of amphetamine reward, an effect dependent on a period of sexual reward abstinence. We previously showed that ΔFosB in the nucleus accumbens (NAc) is a key mediator of this cross-sensitization, potentially via dopamine receptor activation. However, the role of mesolimbic dopamine for sexual behavior or cross-sensitization between natural and drug reward is unknown. This was tested using inhibitory designer receptors exclusively activated by designer drugs in ventral tegmental area (VTA) dopamine cells. rAAV5/hSvn-DIO-hm4D-mCherry was injected into the VTA of TH::Cre adult male rats. Males received clozapine N-oxide (CNO) or vehicle injections before each of 5 consecutive days of mating or handling. Following an abstinence period of 7 d, males were tested for amphetamine conditioned place preference (CPP). Next, males were injected with CNO or vehicle before mating or handling for analysis of mating-induced cFos, sex experience-induced ΔFosB, and reduction of VTA dopamine soma size. Results showed that CNO did not affect mating behavior. Instead, CNO prevented sexual experience-induced cross-sensitization of amphetamine CPP, ΔFosB in the NAc and medial prefrontal cortex, and decreases in VTA dopamine soma size. Expression of hm4D-mCherry was specific to VTA dopamine cells and CNO blocked excitation and mating-induced cFos expression in VTA dopamine cells. These findings provide direct evidence that VTA dopamine activation is not required for initiation or performance of sexual behavior. Instead, VTA dopamine directly contributes to increased vulnerability for drug use following loss of natural reward by causing neuroplasticity in the mesolimbic pathway during the natural reward experience. SIGNIFICANCE STATEMENT: Drugs of abuse act on the neural pathways that mediate natural reward learning and memory. Exposure to natural reward behaviors can alter subsequent drug-related reward. Specifically, experience with sexual behavior, followed by a period of abstinence from sexual behavior, causes increased reward for amphetamine in male rats. This study demonstrates that activation of ventral tegmental area dopamine neurons during sexual experience regulates cross-sensitization of amphetamine reward. Finally, ventral tegmental area dopamine cell activation is essential for experience-induced neural adaptations in the nucleus accumbens, prefrontal cortex, and ventral tegmental area. These findings demonstrate a role of mesolimbic dopamine in the interaction between natural and drug rewards, and identify mesolimbic dopamine as a key mediator of changes in vulnerability for drug use after loss of natural reward.

Funding information:
  • NIMH NIH HHS - R01 MH101130(United States)

Multi-tiered Reorganization of the Genome during B Cell Affinity Maturation Anchored by a Germinal Center-Specific Locus Control Region.

  • Bunting KL
  • Immunity
  • 2016 Sep 20

Literature context:


Abstract:

During the humoral immune response, B cells undergo a dramatic change in phenotype to enable antibody affinity maturation in germinal centers (GCs). Using genome-wide chromosomal conformation capture (Hi-C), we found that GC B cells undergo massive reorganization of the genomic architecture that encodes the GC B cell transcriptome. Coordinate expression of genes that specify the GC B cell phenotype-most prominently BCL6-was achieved through a multilayered chromatin reorganization process involving (1) increased promoter connectivity, (2) formation of enhancer networks, (3) 5' to 3' gene looping, and (4) merging of gene neighborhoods that share active epigenetic marks. BCL6 was an anchor point for the formation of GC-specific gene and enhancer loops on chromosome 3. Deletion of a GC-specific, highly interactive locus control region upstream of Bcl6 abrogated GC formation in mice. Thus, large-scale and multi-tiered genomic three-dimensional reorganization is required for coordinate expression of phenotype-driving gene sets that determine the unique characteristics of GC B cells.

Funding information:
  • NICHD NIH HHS - R01 HD050820(United States)

Individual sympathetic postganglionic neurons coinnervate myenteric ganglia and smooth muscle layers in the gastrointestinal tract of the rat.

  • Walter GC
  • J. Comp. Neurol.
  • 2016 Sep 1

Literature context:


Abstract:

A full description of the terminal architecture of sympathetic axons innervating the gastrointestinal (GI) tract has not been available. To label sympathetic fibers projecting to the gut muscle wall, dextran biotin was injected into the celiac and superior mesenteric ganglia (CSMG) of rats. Nine days postinjection, animals were euthanized and stomachs and small intestines were processed as whole mounts (submucosa and mucosa removed) to examine CSMG efferent terminals. Myenteric neurons were counterstained with Cuprolinic Blue; catecholaminergic axons were stained immunohistochemically for tyrosine hydroxylase. Essentially all dextran-labeled axons (135 of 136 sampled) were tyrosine hydroxylase-positive. Complete postganglionic arbors (n = 154) in the muscle wall were digitized and analyzed morphometrically. Individual sympathetic axons formed complex arbors of varicose neurites within myenteric ganglia/primary plexus and, concomitantly, long rectilinear arrays of neurites within circular muscle/secondary plexus or longitudinal muscle/tertiary plexus. Very few CSMG neurons projected exclusively (i.e., ∼100% of an arbor's varicose branches) to myenteric plexus (∼2%) or smooth muscle (∼14%). With less stringent inclusion criteria (i.e., ≥85% of an axon's varicose branches), larger minorities of neurons projected predominantly to either myenteric plexus (∼13%) or smooth muscle (∼27%). The majority (i.e., ∼60%) of all individual CSMG postganglionics formed mixed, heterotypic arbors that coinnervated extensively (>15% of their varicose branches per target) both myenteric ganglia and smooth muscle. The fact that ∼87% of all sympathetics projected either extensively or even predominantly to smooth muscle, while simultaneously contacting myenteric plexus, is consistent with the view that these neurons control GI muscle directly, if not exclusively. J. Comp. Neurol. 524:2577-2603, 2016. © 2016 Wiley Periodicals, Inc.

Funding information:
  • NIMH NIH HHS - U01 MH105971(United States)

Vagal Intramuscular Arrays: The Specialized Mechanoreceptor Arbors That Innervate the Smooth Muscle Layers of the Stomach Examined in the Rat.

  • Powley TL
  • J. Comp. Neurol.
  • 2016 Mar 1

Literature context:


Abstract:

The fundamental roles that the stomach plays in ingestion and digestion notwithstanding, little morphological information is available on vagal intramuscular arrays (IMAs), the afferents that innervate gastric smooth muscle. To characterize IMAs better, rats were given injections of dextran biotin in the nodose ganglia, and, after tracer transport, stomach whole mounts were collected. Specimens were processed for avidin-biotin permanent labeling, and subsets of the whole mounts were immunohistochemically processed for c-Kit or stained with cuprolinic blue. IMAs (n = 184) were digitized for morphometry and mapping. Throughout the gastric muscle wall, IMAs possessed common phenotypic features. Each IMA was generated by a parent neurite arborizing extensively, forming an array of multiple (mean = 212) branches averaging 193 µm in length. These branches paralleled, and coursed in apposition with, bundles of muscle fibers and interstitial cells of Cajal. Individual arrays averaged 4.3 mm in length and innervated volumes of muscle sheet, presumptive receptive fields, averaging 0.1 mm(3) . Evaluated by region and by muscle sheet, IMAs displayed architectural adaptations to the different loci. A subset (32%) of circular muscle IMAs issued specialized polymorphic collaterals to myenteric ganglia, and a subset (41%) of antral longitudinal muscle IMAs formed specialized net endings associated with the serosal boundary. IMAs were concentrated in regional patterns that correlated with the unique biomechanical adaptations of the stomach, specifically proximal stomach reservoir functions and antral emptying operations. Overall, the structural adaptations and distributions of the IMAs were consonant with the hypothesized stretch receptor roles of the afferents.