As diurnal rodents with a well-developed visual system, squirrels provide a useful comparison of visual system organization with other highly visual mammals such as tree shrews and primates. Here, we describe the projection pattern of gray squirrel superior colliculus (SC) with the large and well-differentiated pulvinar complex. Our anatomical results support the conclusion that the pulvinar complex of squirrels consists of four distinct nuclei. The caudal (C) nucleus, distinct in cytochrome oxidase (CO), acetylcholinesterase (AChE), and vesicular glutamate transporter-2 (VGluT2) preparations, received widespread projections from the ipsilateral SC, although a crude retinotopic organization was suggested. The caudal nucleus also received weaker projections from the contralateral SC. The caudal nucleus also projects back to the ipsilateral SC. Lateral (RLl) and medial (RLm) parts of the previously defined rostral lateral pulvinar (RL) were architectonically distinct, and each nucleus received its own retinotopic pattern of focused ipsilateral SC projections. The SC did not project to the rostral medial (RM) nucleus of the pulvinar. SC injections also revealed ipsilateral connections with the dorsal and ventral lateral geniculate nuclei, nuclei of the pretectum, and nucleus of the brachium of the inferior colliculus and bilateral connections with the parabigeminal nuclei. Comparisons with other rodents suggest that a variously named caudal nucleus, which relays visual inputs from the SC to temporal visual cortex, is common to all rodents and possibly most mammals. RM and RL divisions of the pulvinar complex also appear to have homologues in other rodents.

The ANP32 family of proteins have been implicated in neuronal function through biochemical and cellular biology studies in neurons, as well as by recent behavioural studies of a gene-trapped loss-of-function mutation of Anp32e in mice, particularly with respect to fine motor function. A second targeted allele of the Anp32e, however, did not appear to demonstrate neurological phenotypes.

Early life radiation exposure causes abnormal brain development, leading to adult depression. However, few studies have been conducted to explore pre- or post-natal irradiation-induced depression-related neuropathological changes. Relevant molecular mechanisms are also poorly understood. We induced adult depression by irradiation of mice at postnatal day 3 (P3) to reveal hippocampal neuropathological changes and investigate their molecular mechanism, focusing on MicroRNA (miR) and its target mRNA and protein. P3 mice were irradiated by γ-rays with 5Gy, and euthanized at 1, 7 and 120 days after irradiation. A behavioral test was conducted before the animals were euthanized at 120 days after irradiation. The animal brains were used for different studies including immunohistochemistry, CAP-miRSeq, Real-Time Quantitative Reverse Transcription PCR (qRT-PCR) and western blotting. The interaction of miR-34a-5p and its target T-cell intracytoplasmic antigen-1 (Tia1) was confirmed by luciferase reporter assay. Overexpression of Tia1 in a neural stem cell (NSC) model was used to further validate findings from the mouse model. Irradiation with 5 Gy at P3 induced depression in adult mice. Animal hippocampal pathological changes included hypoplasia of the infrapyramidal blade of the stratum granulosum, aberrant and impaired cell division, and neurogenesis in the dentate gyrus. At the molecular level, upregulation of miR-34a-5p and downregulation of Tia1 mRNA were observed in both animal and neural stem cell models. The luciferase reporter assay and gene transfection studies further confirmed a direct interaction between miR-43a-5p and Tia1. Our results indicate that the early life γ-radiation-activated miR-43a-5p/Tia1 pathway is involved in the pathogenesis of adult depression. This novel finding may provide a new therapeutic target by inhibiting the miR-43a-5p/Tia1 pathway to prevent radiation-induced pathogenesis of depression.

The pulvinar complex of prosimian primates is not as architectonically differentiated as that of anthropoid primates. Thus, the functional subdivisions of the complex have been more difficult to determine. In the present study, we related patterns of connections of cortical visual areas (primary visual area, V1; secondary visual area, V2; and middle temporal visual area, MT) as well as the superior colliculus of the visual midbrain, with subdivisions of the pulvinar complex of prosimian galagos (Otolemur garnetti) that were revealed in brain sections processed for cell bodies (Nissl), cytochrome oxidase, or myelin. As in other primates, the architectonic methods allowed us to distinguish the lateral pulvinar (PL) and inferior pulvinar (PI) as major divisions of the visual pulvinar. The connection patterns further allowed us to divide PI into a large central nucleus (PIc), a medial nucleus (PIm), and a posterior nucleus (PIp). Both PL and PIc have separate topographic patterns of connections with V1 and V2. A third, posterior division of PI, PIp, does not appear to project to V1 and V2 and is further distinguished by receiving inputs from the superior colliculus. All these subdivisions of PI project to MT. The evidence suggests that PL of galagos contains a single, large nucleus, as in monkeys, and that PI may have only three subdivisions, rather than the four subdivisions of monkeys. In addition, the cortical projections of PI nuclei are more widespread than those in monkeys. Thus, the pulvinar nuclei in prosimian primates and anthropoid primates have evolved along somewhat different paths.

Pregnenolone belongs to a class of endogenous neurosteroids in the central nervous system (CNS), which has been suggested to enhance cognitive functions through GABA(A) receptor signaling by its metabolites. It has been shown that the level of pregnenolone is altered in certain brain areas of schizophrenic patients, and clozapine enhances pregnenolone in the CNS in rats, suggesting that pregnenolone could be used to treat certain symptoms of schizophrenia. In addition, early phase proof-of-concept clinical trials have indicated that pregnenolone is effective in reducing the negative symptoms and cognitive deficits of schizophrenia patients. Here, we evaluate the actions of pregnenolone on a mouse model for schizophrenia, the dopamine transporter knockout mouse (DAT KO). DAT KO mice mirror certain symptoms evident in patients with schizophrenia, such as the psychomotor agitation, stereotypy, deficits of prepulse inhibition and cognitive impairments. Following acute treatment, pregnenolone was found to reduce the hyperlocomotion, stereotypic bouts and pre-pulse inhibition (PPI) deficits in DAT KO mice in a dose-dependent manner. At 60 mg/kg of pregnenolone, there were no significant differences in locomotor activities and stereotypy between wild-type and DAT KO mice. Similarly, acute treatment of 60 mg/kg of pregnenolone fully rescued PPI deficits of DAT KO mice. Following chronic treatment with pregnenolone at 60 mg/kg, the cognitive deficits of DAT KO mice were rescued in the paradigms of novel object recognition test and social transmission of food preference test. Pregnenolone thus holds promise as a therapeutic candidate in schizophrenia.

The temporal cortex of grey squirrels contains three architectonically distinct regions. One of these regions, the temporal anterior (Ta) region has been identified in previous physiological and anatomical studies as containing several areas that are largely auditory in function. Consistent with this evidence, Ta has architectonic features that are internally somewhat variable, but overall sensory in nature. In contrast, the caudally adjoining temporal intermediate region (Ti) has architectonic features that suggest higher order and possibly multisensory processing. Finally, the most caudal region, composed of previously defined temporal medial (Tm) and temporal posterior (Tp) fields, again has more of the appearance of sensory cortex. To understand their functional roles better, we injected anatomical tracers into these regions to reveal their thalamic connections. As expected, the dorsal portion of Ta, containing two primary or primary-like auditory areas, received inputs from the ventral and magnocellular divisions of the auditory medial geniculate complex (MGv and MGm). The most caudal region, Tm plus Tp, received inputs from the large visual pulvinar of squirrels, possibly accounting for the sensory architectonic characteristics of this region. However, Tp additionally receives inputs from the magnocellular (MGm) and dorsal (MGd) divisions of the medial geniculate complex, implicating Tp in multisensory processing. Finally, the middle region, Ti, had auditory inputs from MGd and MGm, but not from the visual pulvinar, providing evidence that Ti has higher order auditory functions. The results indicate that the architectonically distinct regions of temporal cortex of squirrels are also functionally distinct. Understanding how temporal cortex is functionally organized in squirrels can guide interpretations of temporal cortex organization in other rodents in which architectonic subdivisions are not as obvious.

The effect of acute irradiation with 5Gy or fractionated exposure with 0.5Gy continuously for 10days (a total dose of 5Gy) was evaluated in an immature BALB/c mouse model. Radioprotective effect of ursolic acid (at 25mg/kg/daily administered 1h after acute or each of fractionated irradiations, and continuously for 30days) was also investigated. We found that both acute and fractionated irradiation at a total dose of 5Gy did not induce any mortality within 30days after exposure to postnatal day 26 (P26) BALB/c mice, but reduced animal weigh gain in the first few weeks. At 90days after irradiation, the weight of animals with acute irradiation was still significantly lower than the control group; no significant difference though was observed for those fractionatedly exposed mice compared to the control group. Behavioral tests indicated that acute irradiation at 5Gy induced deficits in learning and memory in the contextual fear conditioning test. The memory for novel object recognition was also impaired. Similar changes were not observed in mice with fractionated irradiation. Immunohistochemical study demonstrated clearly that acute and fractionated irradiations induced impairment of neurogenesis in the subgranular zone (SGZ) of the dentate gyrus although fractionated exposure induced much lesser loss of newly generated neurons. Ursolic acid administered at 25mg/kg/daily for 30days after irradiation greatly improved acute irradiation-induced deficits in contextual learning and memory and in novel object recognition memory although it exacerbated radiation-induced reduction of neurogenesis in SGZ.

Baicalein (BE) has both antioxidant and anti-inflammatory effects. It has also been reported able to improve cerebral blood circulation in brain ischemic injury. However, its chronic efficacy and metabolomics in Alzheimer's disease (AD) remain unknown. In this study, BE at 80 mg/kg was administrated through the oral route in J20 AD transgenic mice aged from aged 4 months to aged 10 months. Metabolic- and neurobehavioural phenotyping was done before and after 6 months' treatment to evaluate the drug efficacy and the relevant mechanisms. Meanwhile, molecular docking was used to study the binding affinity of BE and poly (ADP-ribose) polymerase-1 (PARP-1) which is related to neuronal injury. The open field test showed that BE could suppress hyperactivity in J20 mice and increase the frequency of the target quadrant crossing in the Morris Water Maze test. More importantly, BE restored cerebral blood flow back to the normal level after the chronic treatment. A 1H NMR-based metabolomics study showed that BE treatment could restore the tricarboxylic acid cycle in plasma. And such a treatment could suppress oxidative stress, inhibit neuroinflammation, alleviate mitochondrial dysfunction, improve neurotransmission, and restore amino homeostasis via starch and sucrose metabolism and glycolipid metabolism in the cortex and hippocampus, which could affect the behavioural and cerebral blood flow. These findings showed that BE is a potential therapeutic agent for AD.

Forceps, clamps, and haemostats are essential surgical tools required for all surgical interventions. While they are widely used to grasp, hold, and manipulate soft tissue, their metallic rigid structure may cause tissue damage due to the potential risk of applying excessive gripping forces. Soft pneumatic surgical grippers fabricated by silicone elastomeric materials with low Young's modulus may offer a promising solution to minimize this unintentional damage due to their inherent excellent compliance and compressibility. The goal of this work is to evaluate and compare the grip-induced nerve damage caused by the soft pneumatic elastomeric gripper and conventional haemostats during surgical manipulation. Twenty-four Wistar rats (male, seven weeks) are subjected to sciatic nerve compression (right hind limb) using the soft pneumatic elastomer gripper and haemostats. A histopathological analysis is conducted at different time-points (Day 0, Day 3, Day 7 and Day 13) after the nerve compression to examine the morphological tissue changes between the rats in the 'soft gripper' group and the 'haemostats' group. A free walking analysis is also performed to examine the walking function of the rats after recovery from different time points. Comparing the rigid haemostats and soft gripper groups, there is a visible difference in the degree of axonal vacuolar degeneration between the groups, which could suggest the presence of substantial nerve damage in the 'haemostats' group. The rats in the haemostats group exhibited reduced right hind paw pressure and paw size after the nerve compression. It shows that the rats tend not to exert more force on the affected right hind limb in the haemostats group compared to the soft gripper group. In addition, the stance duration was reduced in the injured right hind limb compared to the normal left hind limb in the haemostats group. These observations show that the soft pneumatic surgical gripper made of silicone elastomeric materials might reduce the severity of grip-induced damage by providing a safe compliant grip compared to the conventional haemostats. The soft pneumatic elastomer gripper could complement the current surgical gripping tool in delicate tissue manipulation.

TDP-43 aggregates are the defining pathological hallmark for amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Strikingly, these TDP-43 proteinopathies are also found in other neurodegenerative diseases, including Alzheimer's disease and are prevalent in the brains of old-aged humans. Furthermore, disease-causal mutations in TDP-43 have been identified for ALS and FTD. Collectively, the evidence indicates that TDP-43 dysfunctions lead to motor and cognitive deficits. To determine whether the mouse line expressing an ALS-linked mutation in TDP-43 (Q331K) can be used to study ALS-FTD spectrum disorders, we performed a systematic and longitudinal behavioral assessment that covered motor and cognitive functions. Deficits in motor and cognitive abilities were observed as early as 3 months of age and persisted through to 12 months of age. Within the cognitive modalities, the hippocampus-mediated spatial learning and memory, and contextual fear conditioning, were normal; whereas the frontal cortex-mediated working memory and cognitive flexibility were impaired. Biochemically, the human TDP-43 transgene downregulates endogenous mouse TDP-43 mRNA and protein, resulting in human TDP-43 protein that is comparable with the physiological level in cerebral cortex and hippocampus. Furthermore, Q331K TDP-43 is largely retained at the nucleus without apparent aggregates. Taken together, our data suggest that motor and frontal cortex may be more vulnerable to disease-linked mutation in TDP-43 and, this mouse model may be used to assess ALS-FTD-related spectrum diseases and the molecular underpinnings associated with the phenotypes.

Dysregulations in the brain serotonergic system and exposure to environmental stressors have been implicated in the development of major depressive disorder. Here, we investigate the interactions between the stress and serotonergic systems by characterizing the behavioral and biochemical effects of chronic stress applied during early-life or adulthood in wild type (WT) mice and mice with deficient tryptophan hydroxylase 2 (TPH2) function. We showed that chronic mild stress applied in adulthood did not affect the behaviors and serotonin levels of WT and TPH2 knock-in (KI) mice. Whereas, maternal separation (MS) stress increased anxiety- and depressive-like behaviors of WT mice, with no detectable behavioral changes in TPH2 KI mice. Biochemically, we found that MS WT mice had reduced brain serotonin levels, which was attributed to increased expression of monoamine oxidase A (MAO A). The increased MAO A expression was detected in MS WT mice at 4 weeks old and adulthood. No change in TPH2 expression was detected. To determine whether a pharmacological stressor, dexamethasone (Dex), will result in similar biochemical results obtained from MS, we used an in vitro system, SH-SY5Y cells, and found that Dex treatment resulted in increased MAO A expression levels. We then treated WT mice with Dex for 5 days, either during postnatal days 7-11 or adulthood. Both groups of Dex treated WT mice had reduced basal corticosterone and glucocorticoid receptors expression levels. However, only Dex treatment during PND7-11 resulted in reduced serotonin levels and increased MAO A expression. Just as with MS WT mice, TPH2 expression in PND7-11 Dex-treated WT mice was unaffected. Taken together, our findings suggest that both environmental and pharmacological stressors affect the expression of MAO A, and not TPH2, when applied during the critical postnatal period. This leads to long-lasting perturbations in the serotonergic system, and results in anxiety- and depressive-like behaviors.

The architectonic features of the ventroposterior nucleus (VP) were visualized in coronal brain sections from two macaque monkeys, two owl monkeys, two squirrel monkeys, and three galagos that were processed for cytochrome oxidase, Nissl bodies, or the vesicular glutamate transporter 2 (vGluT2). The traditional ventroposterior medial (VPM) and ventroposterior lateral (VPL) subnuclei were easily identified, as well as the forelimb and hindlimb compartments of VPL, as they were separated by poorly staining, cell-poor septa. Septa also separated other cell groups within VPM and VPL, specifically in the medial compartment of VPL representing the hand (hand VPL). In one squirrel monkey and one galago we demonstrated that these five groups of cells represent digits 1-5 in a mediolateral sequence by injecting tracers into the cortical representation of single digits, defined by microelectrode recordings, and relating concentrations of labeled neurons to specific cell groups in hand VPL. The results establish the existence of septa that isolate the representation of the five digits in VPL of primates and demonstrate that the isolated cell groups represent digits 1-5 in a mediolateral sequence. The present results show that the septa are especially prominent in brain sections processed for vGluT2, which is expressed in the synaptic terminals of excitatory neurons in most nuclei of the brainstem and thalamus. As vGluT2 is expressed in the synaptic terminations from dorsal columns and trigeminal brainstem nuclei, the effectiveness of vGluT2 preparations in revealing septa in VP likely reflects a lack of synapses using glutamate in the septa.

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) represent two ends of the same disease spectrum of adult-onset neurodegenerative diseases that affect the motor and cognitive functions, respectively. Multiple common genetic loci such as fused in sarcoma (FUS) have been identified to play a role in ALS and FTD etiology. Current studies indicate that FUS mutations incur gain-of-toxic functions to drive ALS pathogenesis. However, how the disease-linked mutations of FUS affect cognition remains elusive. Using a mouse model expressing an ALS-linked human FUS mutation (R514G-FUS) that mimics endogenous expression patterns, we found that FUS proteins showed an age-dependent accumulation of FUS proteins despite the downregulation of mouse FUS mRNA by the R514G-FUS protein during aging. Furthermore, these mice developed cognitive deficits accompanied by a reduction in spine density and long-term potentiation (LTP) within the hippocampus. At the physiological expression level, mutant FUS is distributed in the nucleus and cytosol without apparent FUS aggregates or nuclear envelope defects. Unbiased transcriptomic analysis revealed a deregulation of genes that cluster in pathways involved in nonsense-mediated decay, protein homeostasis, and mitochondrial functions. Furthermore, the use of in vivo functional imaging demonstrated widespread reduction in cortical volumes but enhanced functional connectivity between hippocampus, basal ganglia and neocortex in R514G-FUS mice. Hence, our findings suggest that disease-linked mutation in FUS may lead to changes in proteostasis and mitochondrial dysfunction that in turn affect brain structure and connectivity resulting in cognitive deficits.

Accumulating evidence suggests that disruptions in brain energy metabolism may be a key player in the pathogenesis of Alzheimer's disease (AD). Pioglitazone (PIO) has been found to exert beneficial effects on metabolic dysfunction in many AD preclinical studies. However, limited success in clinical trials remains an obstacle to its development for the treatment of AD. PIO's poor brain penetration was often cited as a contributing factor to the lack of clinical benefit. In this study, we prepared PIO-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles and administered them as suspended nanoparticles via nebulization. Preliminary investigation of drug distribution to the brain revealed comparatively reduced systemic exposure after administering PIO nanoparticles via the intranasal route. In vitro, extracellular flux analysis showed significantly raised spare respiratory capacity when cells were treated with low-dose PIO nanoparticles. Tg2576 transgenic mice treated with low-dose PIO nanoparticles over four months exhibited an overall trend of reduced hyperactivity in open field tests but did not show any visible effect on alternation rates in the Y-maze task. Subsequent 1H NMR-based metabolic profiling of their plasma and different brain regions revealed differences in metabolic profiles in the cerebellum, cortex, and hippocampus of Tg2576 mice after long-term PIO treatment, but not in their midbrain and plasma. In particular, the specificity of PIO's treatment effects on perturbed amino acid metabolism was observed in the cortex of transgenic mice with increases in alanine and N-acetylaspartate levels, supporting the notion that PIO treatment exerts beneficial effects on impaired energy metabolism associated with AD. In conclusion, inhalation exposure to PIO nanoparticles presents an exciting opportunity that this drug could be administered intranasally at a much lower dose while achieving a sufficient level in the brain to elicit metabolic benefits at an early stage of AD but with reduced systemic exposure.