Depressed patients suffer from cognitive dysfunction, including memory deficits. Acute serotonin (5-HT) depletion impairs memory and mood in vulnerable patients. The investigational multimodal acting antidepressant vortioxetine is a 5-HT3, 5-HT7 and 5-HT1D receptor antagonist, 5-HT1B receptor partial agonist, 5-HT1A receptor agonist and 5-HT transporter (SERT) inhibitor that enhances memory in normal rats in novel object recognition (NOR) and conditioned fear (Mørk et al., 2013). We hypothesized that vortioxetine's 5-HT receptor mechanisms are involved in its memory effects, and therefore investigated these effects in 5-HT depleted rats. Four injections of the irreversible tryptophan hydroxylase inhibitor 4-chloro-dl-phenylalanine methyl ester hydrochloride (PCPA, 86mg/kg, s.c.) induced 5-HT depletion, as measured in hippocampal homogenate and microdialysate. The effects of acute challenge with vortioxetine or the 5-HT releaser fenfluramine on extracellular 5-HT were measured in PCPA-treated and control rats. PCPA's effects on NOR and spontaneous alternation (SA) performance were assessed along with the effects of acute treatment with 5-hydroxy-l-tryptophan (5-HTP), vortioxetine, the selective 5-HT reuptake inhibitor escitalopram, or the 5-HT norepinephrine reuptake inhibitor duloxetine. SERT occupancies were estimated by ex vivo autoradiography. PCPA depleted central 5-HT by >90% in tissue and microdialysate, and impaired NOR and SA performance. Restoring central 5-HT with 5-HTP reversed these deficits. At similar SERT occupancies (>90%) vortioxetine, but not escitalopram or duloxetine, restored memory performance. Acute fenfluramine significantly increased extracellular 5-HT in control and PCPA-treated rats, while vortioxetine did so only in control rats. Thus, vortioxetine restores 5-HT depletion impaired memory performance in rats through one or more of its receptor activities.

Ketamine is a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist that has been shown to induce a rapid antidepressant effect in treatment-resistant patients. Vortioxetine is a multimodal-acting antidepressant that exert its therapeutic activity through serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibition and modulation of several 5-HT receptors. In clinical trials, vortioxetine improves depression symptoms and cognitive dysfunction. Neuroplasticity as well as serotonergic and glutamatergic signaling attain significant roles in depression pathophysiology and antidepressant responses. Here, we investigate the effects of ketamine and vortioxetine on gene expression related to serotonergic and glutamatergic neurotransmission as well as neuroplasticity and compare them to those of the selective serotonin reuptake inhibitor fluoxetine. Rats were injected with fluoxetine (10mg/kg), ketamine (15mg/kg), or vortioxetine (10mg/kg) at 2, 8, 12, or 27h prior to harvesting of the frontal cortex and hippocampus. mRNA levels were measured by real-time quantitative polymerase chain reaction (qPCR). The main finding was that vortioxetine enhanced plasticity-related gene expression (Mtor, Mglur1, Pkcα, Homer3, Spinophilin, and Synapsin3) in the frontal cortex at 8h after a single dose. Ingenuity pathway analysis of this subset of data identified a biological network that was engaged by vortioxetine and is plausibly associated with neuroplasticity. Transcript levels had returned to baseline levels 12h after injection. Only minor effects on gene expression were found for ketamine or fluoxetine. In conclusion, acute vortioxetine, but not fluoxetine or ketamine, transiently increased plasticity-related gene expression in the frontal cortex. These effects may be ascribed to the direct 5-HT receptor activities of vortioxetine.

Progranulin (PGRN), a widely secreted growth factor, is involved in multiple biological functions, and mutations located within the PGRN gene (GRN) are a major cause of frontotemporal lobar degeneration with TDP-43-positive inclusions (FLTD-TDP). In light of recent reports suggesting PGRN functions as a protective neurotrophic factor and that sortilin (SORT1) is a neuronal receptor for PGRN, we used a Sort1-deficient (Sort1-/-) murine primary hippocampal neuron model to investigate whether PGRN's neurotrophic effects are dependent on SORT1. We sought to elucidate this relationship to determine what role SORT1, as a regulator of PGRN levels, plays in modulating PGRN's neurotrophic effects.

Attention impairment is a common feature of Major Depressive Disorder (MDD), and MDD-associated cognitive dysfunction may play an important role in determining functional status among this patient population. Vortioxetine is a multimodal antidepressant that may improve some aspects of cognitive function in MDD patients, and may indirectly increase glutamate neurotransmission in brain regions classically associated with attention function. Previous non-clinical research suggests that vortioxetine has limited effects on attention. This laboratory previously found that vortioxetine did not improve attention function in animals impaired by acute scopolamine administration, using the visual signal detection task (VSDT). However, vortioxetine has limited effects on acetylcholinergic neurotransmission, and thus it is possible that attention impaired by other mechanisms would be attenuated by vortioxetine. This study sought to investigate whether acute vortioxetine administration can attenuate VSDT impairments and hyperlocomotion induced by the non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist MK-801. We found that acute vortioxetine administration had no effect on VSDT performance on its own, but potentiated MK-801-induced VSDT impairments. Furthermore, vortioxetine had no effect on locomotor activity on its own, and did not alter MK-801-induced hyperlocomotion. We further investigated whether vortioxetine's effect on MK-801 could be driven by a kinetic interaction, but found that plasma and brain exposure for vortioxetine and MK-801 were similar whether administered alone or in combination. Thus, it appears that vortioxetine selectively potentiates MK-801-induced impairments in attention without altering its effects on locomotion, and further that this interaction must be pharmacodynamic in nature. A theoretical mechanism for this interaction is discussed.

Spine geometry is considered to reflect synapse function. An accurate and fast method for 3D reconstruction of spines is considered a valuable tool for the purpose of studying spine geometry. Currently, most studies employ manual or automatic reconstruction methods, which still suffer from either poor accuracy or extreme time-consumption. The semi-automatic reconstruction method has previously been described as a time-economic and accurate tool for spine number counting. The purpose of this study is to further validate the semi-automatic method with regards to spine geometry investigation, by comparing it with the manual method as well as with the automatic method.

The health consequences of maternal obesity during pregnancy are disturbing as they may contribute to mental disorders in subsequent generations. We examine the influence of suboptimal grandmaternal diet on potential metabolic and mental health outcome of grand-progenies with a high-fat diet (HFD) manipulation in adulthood in a rat HFD model. Grandmaternal exposure to HFD exacerbated granddaughter's anxiety-like phenotype. Grandmaternal exposure to HFD led to upregulated corticotropin-releasing hormone receptor 2 mRNA expression involved in the stress axis in the male F2 offspring. Thus, we demonstrate that suboptimal grandmaternal diet prior to and during pregnancy and lactation may persist across subsequent generations. These findings have important implications for understanding both individual rates of metabolic and mental health problems and the clinical impact of current global trends towards comorbidity of obesity and depression and anxiety. In conclusion, the effect of grandmaternal HFD consumption during pregnancy on stress axis function and mental disorders may be transmitted to future generations.

We have previously reported that vortioxetine, unlike the selective serotonin reuptake inhibitor fluoxetine, produces a rapid increase of dendritic spine number and Brain Derived Neurotrophic Factor (BDNF)-associated formation of synapses with mitochondrial support in the rat hippocampal CA1 and dentate gyrus. As a continuation of this line of research, and given the putative role of brain glial cells in mediating antidepressant responses the present study investigated early effects of vortioxetine on hippocampal microvasculature and Vascular Endothelial Growth Factor (VEGF) and astrocytes and microglia cells. Rats were treated for 1 week with vortioxetine (1.6 g/kg food chow) or fluoxetine (160 mg/L drinking water) at pharmacologically relevant doses. Stereological principles were used to estimate the number of ALDH1L1 positive astrocytes and Iba1 positive microglia cells, and the length of microvessels in subregions of hippocampus. VEGF protein levels were visualized with immunohistochemistry. Our results showed that vortioxetine significantly increased the number of ramified (resting) microglia and astrocytes accompanied by VEGF level elevation, whereas fluoxetine had no effect after 7 days treatment on these measures. Our findings suggest that astrocytes and microglia may have a role in mediating the pharmacological effects of vortioxetine in rats and that these effects are mediated through mechanisms that go beyond inhibition of the serotonin transporter and may target specific 5-HT receptors. It remains to be investigated whether these findings are relevant for the therapeutic effects of vortioxetine.

The kappa opioid receptor (KOP) system modulates social play responding, however a paucity of studies have examined effects on social motivation and cognition in the absence of play. Prenatal exposure to the anti-epileptic and mood stabiliser valproic acid (VPA) is associated with impaired social responding and altered gene expression of KOP (oprk1) and dynorphin (pdyn) in several brain regions. The present study examined if pharmacological modulation of KOP altered social motivation and cognition, immediate early gene (IEG) and oprk1-pdyn expression in adolescent male rats and rats prenatally exposed to VPA. In control rats, the KOP antagonist DIPPA enhanced sociability, while both DIPPA and the KOP agonist U50488 decreased social novelty preference. In rats exposed prenatally to VPA, neither U50488 nor DIPPA altered sociability or social novelty preference. Analysis of IEG expression revealed that DIPPA reduced expression of egr-1 expression in the prefrontal cortex of control rats and U50488 increased junb expression in the PFC of both control and VPA-exposed rats. VPA-exposed rats exhibited increased expression of oprk1 and pdyn in the prefrontal cortex and amygdala compared with control rats. DIPPA and U50488 increased oprk1 expression in the amygdala of control rats and decreased oprk1 expression in the prefrontal cortex of VPA-exposed rats. Taken together, these data demonstrate that pharmacological modulation of the KOP system alters social motivation and cognition in control rats, an effect not observed in rats prenatally exposed to VPA. These data provide support that prenatal exposure to VPA is associated with alterations in the expression and functionality of KOP system.

Recombinant adeno-associated virus (rAAV) vectors have emerged as the safe vehicles of choice for long-term gene transfer in mammalian nervous system. Recombinant adeno-associated virus-mediated localized gene transfer in adult nervous system following direct inoculation, that is, intracerebral or intrathecal, is well documented. However, recombinant adeno-associated virus delivery in defined neuronal populations in adult animals using less-invasive methods as well as avoiding ectopic gene expression following systemic inoculation remain challenging. Harnessing the capability of some recombinant adeno-associated virus serotypes for retrograde transduction may potentially address such limitations (Note: The term retrograde transduction in this manuscript refers to the uptake of injected recombinant adeno-associated virus particles at nerve terminals, retrograde transport, and subsequent transduction of nerve cell soma). In some studies, recombinant adeno-associated virus serotypes 2/6, 2/8, and 2/9 have been shown to exhibit transduction of connected neuroanatomical tracts in adult animals following lower limb intramuscular recombinant adeno-associated virus delivery in a pattern suggestive of retrograde transduction. However, an extensive side-by-side comparison of these serotypes following intramuscular delivery regarding tissue viral load, and the effect of promoter on transgene expression, has not been performed. Hence, we delivered recombinant adeno-associated virus serotypes 2/6, 2/8, or 2/9 encoding enhanced green fluorescent protein (eGFP), under the control of either cytomegalovirus (CMV) or human synapsin (hSyn) promoter, via a single unilateral hindlimb intramuscular injection in the bicep femoris of adult C57BL/6J mice. Four weeks post injection, we quantified viral load and transgene (enhanced green fluorescent protein) expression in muscle and related nervous tissues. Our data show that the select recombinant adeno-associated virus serotypes transduce sciatic nerve and groups of neurons in the dorsal root ganglia on the injected side, indicating that the intramuscular recombinant adeno-associated virus delivery is useful for achieving gene transfer in local neuroanatomical tracts. We also observed sparse recombinant adeno-associated virus viral delivery or eGFP transduction in lumbar spinal cord and a noticeable lack thereof in brain. Therefore, further improvements in recombinant adeno-associated virus design are warranted to achieve efficient widespread retrograde transduction following intramuscular and possibly other peripheral routes of delivery.

Electroconvulsive therapy (ECT) is a highly effective and fast-acting treatment for depression used in the clinic. Its mechanism of therapeutic action remains uncertain. Previous studies have focused on documenting neuroplasticity in the early phase following electroconvulsive seizures (ECS), an animal model of ECT. Here, we investigate whether changes in synaptic plasticity and nonneuronal plasticity (vascular and mitochondria) are sustained 3 months after repeated ECS trials.

Altered social behaviours are a hallmark of several psychiatric and developmental disorders. Clinical and preclinical data have demonstrated that prenatal exposure to valproic acid (VPA), an anti-epileptic and mood stabiliser, is associated with impaired social responses, and thus provides a useful model for the evaluation of neurobiological mechanisms underlying altered social behaviours. The opioid system is widely recognised to regulate and modulate social behaviours, however few studies have examined if the endogenous opioid system is altered in animal models of social impairment. The present study examined social behavioural responses of adolescent and adult male rats prenatally exposed to VPA, and the expression of mRNA encoding opioid receptors and pre-pro-peptides in discrete brain regions. Adolescent and adult rats prenatally exposed to VPA spent less time engaging in social behaviours in the direct social interaction test and exhibited reduced sociability and social novelty preference in the 3-chamber sociability test, compared to saline-treated counterparts. The VPA-exposed adolescent rats exhibited significantly reduced kappa opioid receptor (oprk1) and pre-pro-dynorphin (pdyn) mRNA expression in the cerebral cortex, and reduced oprk1 and nociceptin/orphanin FQ (oprl1) mRNA expression in the hypothalamus. Adult rats prenatally exposed to VPA exhibited decreased mRNA expression of oprk1 and pdyn in hypothalamus, reduced pro-opiomelanocortin(pomc) in the striatum and an increase in delta opioid receptor (oprd1) mRNA in the amygdaloid cortex, when compared to saline-treated counterparts. Mu opioid receptor (oprm1) mRNA expression did not differ between saline and VPA-exposed rats in any region examined. The data demonstrate that impaired social behaviours in adolescent and adult rats prenatally exposed to VPA is accompanied by altered mRNA expression of opioid receptors and pre-pro-peptides in a region specific manner. In particular, both adolescent and adult VPA-exposed rats exhibit reduced oprk1-pdyn mRNA expression in several brain regions, which are associated with deficits in social behavioural responding in the model.

SORL1 is strongly associated with both sporadic and familial forms of Alzheimer's disease (AD), but a lack of information about alternatively spliced transcripts currently limits our understanding of the role of SORL1 in AD. Here, we describe a SORL1 transcript (SORL1-38b) characterized by inclusion of a novel exon (E38b) that encodes a truncated protein. We identified E38b-containing transcripts in several brain regions, with the highest expression in the cerebellum and showed that SORL1-38b is largely located in neuronal dendrites, which is in contrast to the somatic distribution of transcripts encoding the full-length SORLA protein (SORL1-fl). SORL1-38b transcript levels were significantly reduced in AD cerebellum in three independent cohorts of postmortem brains, whereas no changes were observed for SORL1-fl. A trend of lower 38b transcript level in cerebellum was found for individuals carrying the risk variant at rs2282649 (known as SNP24), although not reaching statistical significance. These findings suggest synaptic functions for SORL1-38b in the brain, uncovering novel aspects of SORL1 that can be further explored in AD research.

Cytosine arabinoside (AraC) is one of the main therapeutic treatments for several types of cancer, including acute myeloid leukaemia. However, after a high-dose AraC chemotherapy regime, patients develop severe neurotoxicity and cell death in the central nervous system leading to cerebellar ataxia, dysarthria, nystagmus, somnolence and drowsiness. AraC induces apoptosis in dividing cells. However, the mechanism by which it leads to neurite degeneration and cell death in mature neurons remains unclear. We hypothesise that the upregulation of the death receptor p75NTR is responsible for AraC-mediated neurodegeneration and cell death in leukaemia patients undergoing AraC treatment. To determine the role of AraC-p75NTR signalling in the cell death of mature neurons, we used mature cerebellar granule neurons' primary cultures from p75NTR knockout and p75NTRCys259 mice. Evaluation of neurite degeneration, cell death and p75NTR signalling was done by immunohistochemistry and immunoblotting. To assess the interaction between AraC and p75NTR, we performed cellular thermal shift and AraTM assays as well as Homo-FRET anisotropy imaging. We show that AraC induces neurite degeneration and programmed cell death of mature cerebellar granule neurons in a p75NTR-dependent manner. Mechanistically, Proline 252 and Cysteine 256 residues facilitate AraC interaction with the transmembrane domain of p75NTR resulting in uncoupling of p75NTR from the NFκB survival pathway. This, in turn, exacerbates the activation of the cell death/JNK pathway by recruitment of TRAF6 to p75NTR. Our findings identify p75NTR as a novel molecular target to develop treatments for counteract AraC-mediated cell death of mature neurons.

The ADAMTS9 rs4607103 C allele is one of the few gene variants proposed to increase the risk of type 2 diabetes through an impairment of insulin sensitivity. We show that the variant is associated with increased expression of the secreted ADAMTS9 and decreased insulin sensitivity and signaling in human skeletal muscle. In line with this, mice lacking Adamts9 selectively in skeletal muscle have improved insulin sensitivity. The molecular link between ADAMTS9 and insulin signaling was characterized further in a model where ADAMTS9 was overexpressed in skeletal muscle. This selective overexpression resulted in decreased insulin signaling presumably mediated through alterations of the integrin β1 signaling pathway and disruption of the intracellular cytoskeletal organization. Furthermore, this led to impaired mitochondrial function in mouse muscle-an observation found to be of translational character because humans carrying the ADAMTS9 risk allele have decreased expression of mitochondrial markers. Finally, we found that the link between ADAMTS9 overexpression and impaired insulin signaling could be due to accumulation of harmful lipid intermediates. Our findings contribute to the understanding of the molecular mechanisms underlying insulin resistance and type 2 diabetes and point to inhibition of ADAMTS9 as a potential novel mode of treating insulin resistance.

Preclinical studies reveal that the multimodal antidepressant vortioxetine enhances long-term potentiation and dendritic branching compared to a selective serotonin reuptake inhibitor (SSRI). In the present study, we investigated vortioxetine׳s effects on spines and dendritic morphology in rat hippocampus at two time points compared to the SSRI, fluoxetine. Rats were dosed for 1 and 4 weeks with vortioxetine and fluoxetine at doses relevant for antidepressant activity. Dendritic morphology of pyramidal neurons (i.e., dendritic length, dendritic branch, spine number and density, and Sholl analysis) was examined in Golgi-stained sections from hippocampal CA1. After 1 week of treatment, vortioxetine significantly increased spine number (apical and basal dendrites), spine density (only basal), dendritic length (only apical), and dendritic branch number (apical and basal), whereas fluoxetine had no effect. After 4 weeks of treatment, vortioxetine significantly increased all measures of dendritic spine morphology as did fluoxetine except for spine density of basal dendrites. The number of intersections in the apical and basal dendrites was also significantly increased for both treatments after 4 weeks compared to control. In addition, 4 weeks of vortioxetine treatment, but not fluoxetine, promoted a decrease in spine neck length. In conclusion, 1-week vortioxetine treatment induced changes in spine number and density and dendritic morphology, whereas an equivalent dose of fluoxetine had no effects. Decreased spine neck length following 4-week vortioxetine treatment suggests a transition to mature spine morphology. This implies that vortioxetine׳s effects on spine and dendritic morphology are mediated by mechanisms that go beyond serotonin reuptake inhibition.

Vortioxetine, a novel antidepressant with multimodal action, is a serotonin (5-HT)3, 5-HT7 and 5-HT1D receptor antagonist, a 5-HT1B receptor partial agonist, a 5-HT1A receptor agonist and a 5-HT transporter (SERT) inhibitor. Vortioxetine has been shown to improve cognitive performance in several preclinical rat models and in patients with major depressive disorder. Here we investigated the mechanistic basis for these effects by studying the effect of vortioxetine on synaptic transmission, long-term potentiation (LTP), a cellular correlate of learning and memory, and theta oscillations in the rat hippocampus and frontal cortex. Vortioxetine was found to prevent the 5-HT-induced increase in inhibitory post-synaptic potentials recorded from CA1 pyramidal cells, most likely by 5-HT3 receptor antagonism. Vortioxetine also enhanced LTP in the CA1 region of the hippocampus. Finally, vortioxetine increased fronto-cortical theta power during active wake in whole animal electroencephalographic recordings. In comparison, the selective SERT inhibitor escitalopram showed no effect on any of these measures. Taken together, our results indicate that vortioxetine can increase pyramidal cell output, which leads to enhanced synaptic plasticity in the hippocampus. Given the central role of the hippocampus in cognition, these findings may provide a cellular correlate to the observed preclinical and clinical cognition-enhancing effects of vortioxetine.

Neuropeptide S (NPS) has generated substantial interest due to its anxiolytic and fear-attenuating effects in rodents, while a corresponding receptor polymorphism associated with increased NPS receptor (NPSR1) surface expression and efficacy has been implicated in an increased risk of panic disorder in humans. To gain insight into this paradox, we examined the NPS system in rats and mice bred for high anxiety-related behavior (HAB) versus low anxiety-related behavior, and, thereafter, determined the effect of central NPS administration on anxiety- and fear-related behavior. The HAB phenotype was accompanied by lower basal NPS receptor (Npsr1) expression, which we could confirm via in vitro dual luciferase promoter assays. Assessment of shorter Npsr1 promoter constructs containing a sequence mutation that introduces a glucocorticoid receptor transcription factor binding site, confirmed via oligonucleotide pull-down assays, revealed increased HAB promoter activity-an effect that was prevented by dexamethasone. Analogous to the human NPSR1 risk isoform, functional analysis of a synonymous single nucleotide polymorphism in the coding region of HAB rodents revealed that it caused a higher cAMP response to NPS stimulation. Assessment of the behavioral consequence of these differences revealed that intracerebroventricular NPS reversed the hyperanxiety of HAB rodents as well as the impaired cued-fear extinction in HAB rats and the enhanced fear expression in HAB mice, respectively. These results suggest that alterations in the NPS system, conserved across rodents and humans, contribute to innate anxiety and fear, and that HAB rodents are particularly suited to resolve the apparent discrepancy between the preclinical and clinical findings to date.

The rapid and sustained antidepressant properties of ketamine provide evidence of the importance of the glutamatergic system in the neurobiology of depression. The antidepressant-like effects of ketamine are dependent on brain-derived neurotrophic factor (BDNF) and mammalian target of rapamycin (mTOR) in limbic brain areas. The nitrergic system is closely related to the glutamatergic system and generates antidepressant-like effects when blocked. The aim of this study was to investigate whether the behavioural effects induced by the inhibition of nitric oxide (NO) synthesis by aminoguanidine or N-methyl-D-aspartate (NMDA) receptor blockade by ketamine would affect the gene expression of Bdnf and Mtor in the ventromedial prefrontal cortex in rats. The effects of ketamine or aminoguanidine were investigated in Sprague-Dawley (SD) rats, the Flinders Sensitive Line (FSL), a genetic rat model of depression, and their controls, the Flinders Resistant Line (FRL) rats. In the studies, the three protocols evaluated to which the animals/rats were exposed were: (1) pre-test and test sessions of forced swim test (FST), (2) pre-test session of FST alone, or (3) not exposed to the FST. Ketamine and aminoguanidine both induce antidepressant-like effects in SD and FSL rats. Quantitative real-time polymerase chain reaction analyses in SD rats demonstrated that none of the treatments can change the Bdnf or Mtor gene expression, but in FSL rats the treatment with ketamine increased only Bdnf gene expression. The data obtained strengthens the role of NMDA antagonists and NO inhibitors as potential antidepressant drugs, albeit with different effects on Bdnf gene expression.

Electroconvulsive therapy is a fast-acting and efficient treatment of depression used in the clinic. The underlying mechanism of its therapeutic effect is still unclear. However, recovery of synaptic connections and synaptic remodeling is thought to play a critical role for the clinical efficacy obtained from a rapid antidepressant response. Here, we investigated the relationship between synaptic changes and concomitant nonneuronal changes in microvasculature and mitochondria and its relationship to brain-derived neurotrophic factor level changes after repeated electroconvulsive seizures, an animal model of electroconvulsive therapy.

Exposure to maternal stress during pregnancy can have adverse effects on the fetus, which has potential long-term effects on offspring´s development and health. We investigated the kinetics and metabolism of the hormones and amino acids: cortisol, cortisone, tryptophan and serotonin in the term placenta in an ex vivo human placental perfusion model. The placentas used in the experiments were donated from families participating in the Maternal Stress and Placental Function project with a known maternal stress background.