Stress-induced changes in cerebral metabolites, hippocampal volume, and cell proliferation are prevented by antidepressant treatment with tianeptine

The protective effects of Ghrelin/GHSR on hippocampal neurogenesis in CUMS mice

Ghrelin is an orexigenic hormone that also plays an important role in mood disorders. Our previous studies demonstrated that ghrelin administration could protect against depression-like behaviors of chronic unpredictable mild stress (CUMS) in rodents. However, the mechanism related to the effect of ghrelin on CUMS mice has yet to be revealed. This article shows that ghrelin (5 nmol/kg/day for 2 weeks, i.p.) decreased depression-like behaviors induced by CUMS and increased hippocampal integrity (neurogenesis and spine density) measured via Ki67, 5-bromo-2-deoxyuridine (BrdU), doublecortin (DCX) labeling and Golgi-cox staining, which were decreased under CUMS. The behavioral phenotypes of Growth hormone secretagogue receptor (Ghsr)-null and wild type (WT) mice were evaluated under no stress condition and after CUMS exposure to determine the effect of Ghsr knockout on the behavioral phenotypes and stress susceptibility of mice. Ghsr-null mice exhibited depression-like behaviors under no stress condition. CUMS induced similar depression- and anxiety-like behavioral manifestations in both Ghsr-null and WT mice. A similar pattern of behavioral changes was observed after hippocampal GHSR knockdown. Additionally, both Ghsr knockout as well as CUMS exhibited deleterious effects on neurogenesis and spine density in the dentate gyrus (DG). Besides, CCK8 assay and 5-Ethynyl-2'-deoxyuridine (EdU) incorporation assay showed that ghrelin has a proliferative effect on primary cultured hippocampal neural stem cells (NSCs) and this proliferation was blocked by D-Lys3-GHRP-6 (DLS, the antagonist of GHSR, 100 μM) pretreatment. Ghrelin-induced proliferation is associated with the inhibition of G1 arrest, and this inhibition was blocked by LY294002 (specific inhibitor of PI3K, 20 μM). Furthermore, the in vivo data displayed that LY294002 (50 nmol, i.c.v.) can significantly block the antidepressant-like action of exogenous ghrelin treatment. All these results suggest that ghrelin/GHSR signaling maintains the integrity of hippocampus and has an inherent neuroprotective effect whether facing stress or not.

In vivo Hippocampal Serotonin Dynamics in Male and Female Mice: Determining Effects of Acute Escitalopram Using Fast Scan Cyclic Voltammetry

Depression is a highly prevalent psychiatric disorder, impacting females at a rate roughly twice that of males. This disparity has become the focus of many studies which are working to determine if there are environmental or biological underpinnings to depression pathology. The biology of depression is not well understood, but experts agree that a key neurotransmitter of interest is serotonin. Most research on basic serotonin neurochemistry, by us and others, has predominantly focused on male models. Thus, it is now critical to include female models to decipher possible fundamental differences between the sexes that may underlie this disorder. In this paper, we seek to determine any such differences using fast-scan cyclic voltammetry (FSCV) and fast-scan controlled adsorption voltammetry. These techniques allow us to probe the serotonergic system via measurement of evoked and ambient serotonin at carbon fiber microelectrodes (CFMs). Our data reveal no statistical differences, in the hippocampus, in female serotonin chemistry during the different stages of the estrous cycle compared to the mean female response. Furthermore, no difference was observed in evoked serotonin release and reuptake, nor ambient extracellular serotonin levels between male and female mice. We applied a previously developed mathematical model that fits our serotonin signals as a function of several synaptic processes that control the extracellular levels of this transmitter. We used the model to study potential system differences between males and females. One hypothesis brought fourth, that female mice exhibit tighter autoreceptor control of serotonin, is validated via literature and methiothepin challenge. We postulate that this tight regulation may act as a control mechanism against changes in the serotonin signal mediated by estrogen spikes. Importantly, this safety mechanism has no consequence for acutely administered escitalopram’s (ESCIT’s) ability to increase extracellular serotonin between the sexes. This work demonstrates little fundamental differences in in vivo hippocampal serotonin between the sexes, bar control mechanisms in female mice that can be observed under extraneous circumstances. We thus highlight the importance of considering sex as a biological factor in determining pharmacodynamics for personalized medical treatments that involve targeting serotonin receptors.

Stress - (self) eating: Epigenetic regulation of autophagy in response to psychological stress

Autophagy is a constitutive and cytoprotective catabolic process. Aberrations in autophagy lead to a multitude of degenerative disorders, with neurodegeneration being one of the most widely studied autophagy-related disorders. While the field has largely been focusing on the cytosolic constituents and processes of autophagy, recent studies are increasingly appreciating the role of chromatin modifications and epigenetic regulation in autophagy maintenance. Autophagy has been implicated in the regulation of neurogenesis, and disruption of neurogenesis in response to psychological stress is a proximal risk factor for development of neuropsychiatric disorders such as major depressive disorder (MDD). In this review, we will discuss the regulation of autophagy in normal neurogenesis as well as during chronic psychological stress, focusing on the epigenetic control of autophagy in these contexts, and also highlight the lacunae in our understanding of this process. The systematic study of these regulatory mechanisms will provide a novel therapeutic strategy, based on the use epigenetic regulators of autophagy to enhance neurogenesis and potentially alleviate stress-related behavioral disorders.

Adjunctive tianeptine treatment for bipolar disorder: A 24-week randomized, placebo-controlled, maintenance trial

OBJECTIVE

The purpose of this study was to assess the efficacy and tolerability of tianeptine as an adjunctive maintenance treatment for bipolar depression.

METHODS

This is a multicenter double-blind randomized placebo-controlled maintenance trial of adjunctive tianeptine 37.5 mg/day. Participants ( n=161) had a Montgomery-Asberg Depression Rating Scale ⩾12 at entry. After eight weeks of open-label tianeptine treatment, those who responded to tianeptine ( n=69) were randomized to adjunctive tianeptine ( n=36) or placebo ( n=33) in addition to usual treatment. Kaplan-Meier estimates and the Mantel-Cox log-rank test were used to evaluate differences in time to intervention for a mood episode between the tianeptine and placebo groups. We also assessed overall functioning, biological rhythms, quality of life, rates of manic switch and serum brain-derived neurotrophic factor levels.

RESULTS

There were no differences between adjunctive tianeptine or placebo regarding time to intervention or depression scores in the 24-week double-blind controlled phase. Patients in the tianeptine group showed better performance in the letter-number sequencing subtest from the Wechsler Adult Intelligence Scale at the endpoint ( p=0.014). Tianeptine was well tolerated and not associated with higher risk for manic switch compared to placebo.

CONCLUSION

Tianeptine was not more effective than placebo in the maintenance treatment of bipolar depression. There is preliminary evidence suggesting a pro-cognitive effect of tianeptine in working memory compared to placebo.

The possible beneficial effects of creatine for the management of depression

Depression, a highly prevalent neuropsychiatric disorder worldwide, causes a heavy burden for the society and is associated with suicide risk. The treatment of this disorder remains a challenge, since currently available antidepressants provide a slow and, often, incomplete response and cause several side effects that contribute to diminish the adhesion of patients to treatment. In this context, several nutraceuticals have been investigated regarding their possible beneficial effects for the management of this neuropsychiatric disorder. Creatine stands out as a supplement frequently used for ergogenic purpose, but it also is a neuroprotective compound with potential to treat or mitigate a broad range of central nervous systems diseases, including depression. This review presents preclinical and clinical evidence that creatine may exhibit antidepressant properties. The focus is given on the possible molecular mechanisms underlying its effects based on the results obtained with different animal models of depression. Finally, evidence obtained in animal models of depression addressing the possibility that creatine may produce rapid antidepressant effect, similar to ketamine, are also presented and discussed.

Posttraumatic stress disorder, social anxiety disorder and childhood trauma: Differences in hippocampal subfield volume

Volume-based hippocampal findings in Social Anxiety Disorder (SAD) and Posttraumatic Stress Disorder (PTSD) have been inconsistent, with very little investigation of hippocampal subfields. We assessed the effects of early childhood trauma on hippocampal subfields in participants with SAD with and without early childhood trauma and PTSD, compared to healthy controls. The sample comprised 26 participants SAD with early childhood trauma, 22 participants with SAD without early childhood trauma, 17 with PTSD secondary to early childhood trauma and 25 control participants. We used Freesurfer version 6 to determine hippocampal subfield volumes. Findings included significant reduction in right parasubiculum volume between the PTSD group secondary to early childhood trauma and the SAD group without early childhood trauma, as well as a significant reduction in left HATA (Hippocampal Amygdala Transition Area) volume between PTSD with early childhood trauma compared to controls, as well as compared to SAD with early childhood trauma. These findings did withstand correction for multiple resting using the false discovery rate. Our findings of an association of reduced volumes in the parasubiculum and HATA regions with PTSD secondary to childhood trauma are interesting. Further work should investigate whether parasubiculum and HATA regional volume reductions in PTSD are a specific effect of early childhood trauma or a specific manifestation of PTSD pathology. Further work should also be undertaken to determine if hippocampal subfield atrophy is associated with SAD in the setting of early childhood maltreatment.

A Resting-State Functional MR Imaging and Spectroscopy Study of the Dorsal Hippocampus in the Chronic Unpredictable Stress Rat Model

Exposure to chronic stress leads to an array of anatomical, functional, and metabolic changes in the brain that play a key role in triggering psychiatric disorders such as depression. The hippocampus is particularly well known as a target of maladaptive responses to stress. To capture stress-induced changes in metabolic and functional connectivity in the hippocampus, stress-resistant (low-responders) or -susceptible (high-responders) rats exposed to a chronic unpredictable stress paradigm (categorized according to their hormonal and behavioral responses) were assessed by multimodal neuroimaging; the latter was achieved by using localized ¹H MR spectroscopy and resting-state functional MRI (fMRI) at 11,7T data from stressed (n = 25) but also control (n = 15) male Wistar rats.Susceptible animals displayed increased GABA-glutamine (+19%) and glutamate-glutamine (+17%) ratios and decreased levels of macromolecules (-11%); these changes were positively correlated with plasma corticosterone levels. In addition, the neurotransmitter levels showed differential associations with functional connectivity between the hippocampus and the amygdala, the piriform cortex and thalamus between stress-resistant and -susceptible animals. Our observations are consistent with previously reported stress-induced metabolomic changes that suggest overall neurotransmitter dysfunction in the hippocampus. Their association with the fMRI data in this study reveals how local adjustments in neurochemistry relate to changes in the neurocircuitry of the hippocampus, with implications for its stress-associated dysfunctions.SIGNIFICANCE STATEMENT Chronic stress disrupts brain homeostasis, which may increase the vulnerability of susceptible individuals to neuropsychiatric disorders such as depression. Characterization of the differences between stress-resistant and -susceptible individuals on the basis of noninvasive imaging tools, such as magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI), contributes to improved understanding of the mechanisms underpinning individual differences in vulnerability and can facilitate the design of new diagnostic and intervention strategies. Using a combined functional MRI/MRS approach, our results demonstrate that susceptible- and non-susceptible subjects show differential alterations in hippocampal GABA and glutamate metabolism that, in turn, associate with changes in functional connectivity.

Adult mammalian neurogenesis and motivated behaviors

Adult neurogenesis continues to captivate the curiosity of the scientific community; and researchers seem to have a particular interest in identifying the functional implications of such plasticity. While the majority of research focuses on the association between adult neurogenesis and learning and memory (including spatial learning associated with hippocampal neurogenesis and olfactory discrimination associated with neurogenesis in the olfactory system), the following review will explore the link to motivated behaviors. In particular, goal-directed behaviors such as sociosexual, parental, aggressive, as well as depression- and anxiety-like behaviors and their reciprocal association to adult neurogenesis will be evaluated. The review will detail research in humans and other mammalian species. Furthermore, the potential mechanisms underlying these neurogenic alterations will be highlighted. Lastly, the review will conclude with a discussion on the functional significance of these newly generated cells in mediating goal-directed behaviors.

Tianeptine, an atypical pharmacological approach to depression

The introduction of the first antidepressants in the 50s of the 20th century radically changed the treatment of depression, while providing information on pathophysiological aspects of this disease. New antidepressants drugs (agomelatine, tianeptine, vortioxetine) are providing data that give rise to pathophysiological hypotheses of depression that differ from the classic monoaminergic theory. In this sense, tianeptina, an atypical drug by its mechanism of differential action, contributes to clarify that in depression there is more than monoamines. Thus, tianeptine does not modify the rate of extracellular serotonin, so it does not increase or decrease the reuptake of serotonin. Chronic administration of tianeptine does not alter the density or affinity of more than a hundred classical receptors related to depression. Recently, a weak action of tianeptine on Mu opioid receptors has been described that could explain the release of dopamine in the limbic system and its participation in the modulation of glutamatergic mechanisms. These mechanisms support the hypothesis of the possible mechanism of action of this antidepressant. Tianeptine is an antidepressant, with anxiolytic properties, that can improve somatic symptoms. Tianeptine as a glutamatergic modulator, among other mechanisms, allows us to approach depression from a different point of view than other antidepressants.

Cotinine Plus Krill Oil Decreased Depressive Behavior, and Increased Astrocytes Survival in the Hippocampus of Mice Subjected to Restraint Stress

Restraint stress (RS) is a condition affecting millions of people worldwide. The investigation of new therapies to alleviate the consequences of prolonged RS is much needed. Cotinine, a nicotine-derivative, has shown to prevent the decrease in cerebral synaptic density, working memory deficits, anxiety, and depressive-like behavior after prolonged restraint stress (RS) in mice. Furthermore, post-treatment with cotinine reduced the adverse effects of chronic RS on astrocyte survival and architecture. On the other hand, the nutritional supplement krill oil (KO), has shown to be beneficial in decreasing depressive-like behavior and oxidative stress. In this study, in the search for effective preventative treatments to be used in people subjected to reduced mobility, the effect of co-treatment with cotinine plus KO in mice subjected to prolonged RS was investigated. The results show that cotinine plus KO prevented the loss of astrocytes, the appearance of depressive-like behavior and cognitive impairment induced by RS. The use of the combination of cotinine plus KO was more effective than cotinine alone in preventing the depressive-like behavior in the restrained mice. The potential use of this combination to alleviate the psychological effects of reduced mobility is discussed.

Maternal separation induces long-term changes in mineralocorticoid receptor in rats subjected to chronic stress and treated with tianeptine

PURPOSE

The aim of this study was to analyze whether early maternal separation would result in long-term, persistent alterations in stress response in adulthood, altering mineralocorticoid receptor immunoreactivity (MR-ir) in the dorsal hippocampal areas [CA1, CA2, CA3 and dentate gyrus (DG)], paraventricular nucleus of the hypothalamus and medial and central nucleus of the amygdala, key structures involved in stress response regulation. We also analyzed whether chronic treatment with the antidepressant tianeptine reverses these possible changes.

MATERIAL AND METHODS

Male Wistar rats were subjected to daily maternal separation for 4.5 h during 3 weeks or left undisturbed. As adults, they were exposed to chronic stress during 24 days or left undisturbed, and they were also daily treated with tianeptine (10 mg/kg i.p.) or isotonic solution.

RESULTS

In the CA2 and DG areas of the dorsal hippocampus, there was an increase in MR-ir in non-maternally separated and chronic stressed groups. Tianeptine raised MR-ir in the CA3. In the DG, control and maternally separated + chronic stress groups treated with tianeptine showed more MR-ir than their respective vehicle groups. In the paraventricular nucleus, tianeptine decreased MR-ir in non-separated groups, but not in maternally separated rats.

CONCLUSIONS

Our results support findings that early-life events induce long-term changes in stress response regulation, persistent into adulthood, which are manifested during challenges in later life, and that treatment with tianeptine, which tends to attenuate the hypothalamus-pituitary-adrenal axis dysregulation, depends on the individual experience of each rat.

Changes in brain metabolites related to stress resilience: Metabolomic analysis of the hippocampus in a rat model of depression

The ability to cope successfully with stress is known as 'resilience', and those with resilience are not prone to developing depression. One preclinical animal model for depression is the chronic mild stress (CMS) model. There are CMS-resilient (do not manifest anhedonia) and CMS-susceptible (manifest anhedonia) rats. This study aimed to investigate the differences in the profiles of hippocampal metabolites between susceptible and resilient rats, and to identify a biomarker that can distinguish the two. We divided stress-loaded rats into susceptible and resilient types based on their sucrose preference values. We then conducted brain-derived neurotrophic factor (BDNF) quantification and metabolomic analysis in the hippocampus. Compared to the controls, no significant differences were observed in the hippocampal BDNF levels of susceptible and resilient rats. However, the control rats were clearly distinguishable from the susceptible rats in terms of their brain metabolite profiles; the control rats were difficult to distinguish from the resilient rats. CMS model rats showed an increase in the levels of N-acetylaspartate and glutamate, and a decrease in the levels of aspartate and γ-aminobutyric acid in the hippocampus. Of the 12 metabolites measured in the present study, N-acetylaspartate was the only one that could differentiate the three types (control, susceptible, and resilient) of rats. Thus, brain metabolomic analyses can not only distinguish CMS model rats from control rats, but also indicate stress susceptibility. The variation in the levels of N-acetylaspartate in the hippocampus of control, resilient, and susceptible rats demonstrated that it could be a biomarker for stress susceptibility.

Gene Expression in the Hippocampus in a Rat Model of Premenstrual Dysphoric Disorder After Treatment With Baixiangdan Capsules

Objective: To explore the targets, signal regulatory networks and mechanisms involved in Baixiangdan (BXD) capsule regulation of premenstrual dysphoric disorder (PMDD) at the gene transcription level, since the etiology and pathogenesis of PMDD are not well understood.

Methods: The PMDD rat model was prepared using the resident-intruder paradigm. The rats were tested for aggressive behavior, and those with scores in the lowest 30% were used as controls, while rats with scores in the highest 30% were divided into a PMDD model group, BXD administration group and fluoxetine administration group, which were evaluated with open-field tests and aggressive behavior tests. We also analyzed gene expression profiles in the hippocampus for each group, and verified differential expression of genes by real-time PCR.

Results: Before and after BXD or fluoxetine administration, scores in the open-field test exhibited no significant differences. The aggressive behavior of the PMDD model rats was improved to a degree after administration of both substances. Gene chip data indicated that 715 genes were differentially expressed in the control and BXD groups. Other group-to-group comparisons exhibited smaller numbers of differentially expressed genes. The effective targets of both drugs included the Htr2c, Cdh3, Serpinb1a, Ace, Trpv4, Cacna1a, Mapk13, Mapk8, Cyp2c13, and Htr1a genes. The results of real-time PCR tests were in accordance with the gene chip data. Based on the target genes and signaling pathway network analysis, we have elaborated the impact and likely mechanism of BXD in treating PMDD and premenstrual irritability.

Conclusion: Our work contributes to the understanding of PMDD pathogenesis and the mechanisms of BXD treatment. We speculate that the differentially expressed genes could participate in neuroactive ligand-receptor interactions, mitogen-activated protein kinase, calcium, and gamma-aminobutyric acid signal transduction.

Stress assessment by means of heart rate derived from functional near-infrared spectroscopy

Many studies have been carried out in order to detect and quantify the level of mental stress by means of different physiological signals. From the physiological point of view, stress promptly affects brain and cardiac function; therefore, stress can be assessed by analyzing the brain- and heart-related signals more efficiently. Signals produced by functional near-infrared spectroscopy (fNIRS) of the brain together with the heart rate (HR) are employed to assess the stress induced by the Montreal Imaging Stress Task. Two different versions of the HR are used in this study. The first one is the commonly used HR derived from the electrocardiogram (ECG) and is considered as the reference HR (RHR). The other is the HR computed from the fNIRS signal (EHR) by means of an effective combinational algorithm. fNIRS and ECG signals were simultaneously recorded from 10 volunteers, and EHR and RHR are derived from them, respectively. Our results showed a high degree of agreement [r  >  0.9, BAR (Bland Altman ratio) <5  %  ] between the two HR. A principal component analysis/support vector machine-based algorithm for stress classification is developed and applied to the three measurements of fNIRS, EHR, and RHR and a classification accuracy of 78.8%, 94.6%, and 62.2% were obtained for the three measurements, respectively. From these observations, it can be concluded that the EHR carries more useful information with regards to the mental stress than the RHR and fNIRS signals. Therefore, EHR can be used alone or in combination with the fNIRS signal for a more accurate and real-time stress detection and classification.

Elimination of vesicular zinc alters the behavioural and neuroanatomical effects of social defeat stress in mice

Chronic stress can have deleterious effects on mental health, increasing the risk of developing depression or anxiety. But not all individuals are equally affected by stress; some are susceptible while others are more resilient. Understanding the mechanisms that lead to these differing outcomes has been a focus of considerable research. One unexplored mechanism is vesicular zinc – zinc that is released by neurons as a neuromodulator. We examined how chronic stress, induced by repeated social defeat, affects mice that lack vesicular zinc due to genetic deletion of zinc transporter 3 (ZnT3). These mice, unlike wild type mice, did not become socially avoidant of a novel conspecific, suggesting resilience to stress. However, they showed enhanced sensitivity to the potentiating effect of stress on cued fear memory. Thus, the contribution of vesicular zinc to stress susceptibility is not straightforward. Stress also increased anxiety-like behaviour but produced no deficits in a spatial Y-maze test. We found no evidence that microglial activation or hippocampal neurogenesis accounted for the differences in behavioural outcome. Volumetric analysis revealed that ZnT3 KO mice have larger corpus callosum and parietal cortex volumes, and that corpus callosum volume was decreased by stress in ZnT3 KO, but not wild type, mice.

Neuroimmunomodulation in Major Depressive Disorder: Focus on Caspase 1, Inducible Nitric Oxide Synthase, and Interferon-Gamma

Major depressive disorder (MDD) is one of the leading causes of disability worldwide, and its incidence is expected to increase. Despite tremendous efforts to understand its underlying biological mechanisms, MDD pathophysiology remains elusive and pharmacotherapy outcomes are still far from ideal. Low-grade chronic inflammation seems to play a key role in mediating the interface between psychological stress, depressive symptomatology, altered intestinal microbiology, and MDD onset. We review the available pre-clinical and clinical evidence of an involvement of pro-inflammatory pathways in the pathogenesis, treatment, and remission of MDD. We focus on caspase 1, inducible nitric oxide synthase, and interferon gamma, three inflammatory systems dysregulated in MDD. Treatment strategies aiming at targeting such pathways alone or in combination with classical therapies could prove valuable in MDD. Further studies are needed to assess the safety and efficacy of immune modulation in MDD and other psychiatric disorders with neuroinflammatory components.

Differential effects of clomipramine on depression-like behaviors induced by the chronic social defeat paradigm in tree shrews

BACKGROUND

Anhedonia is a hallmark symptom in major depression that reflects deficits in hedonic capacity and it is also linked to motivation for reward. However, studies of the features of motivation in depressed tree shrews are rather sparse.

AIMS

The study aimed to investigate the core feature of depression including lack of interest, motivation reduction, and social avoidance in tree shrews. Furthermore, the effects of the treatment using clomipramine on these depression-like behaviors were assessed.

METHODS

The paradigm of chronic social defeat in tree shrews was used to evaluate the core feature of depression through examining their sucrose preference, break-point for reward, and social interaction.

RESULTS

The results showed that social defeat lowered the curves of the sucrose preference and the break-point, as well as decreased social interaction. The results suggested that the subordinate animals exhibited interest loss, motivational reduction, and social avoidance. After oral treatment with clomipramine (50 mg/kg/day) for four weeks, most of the depression-like behaviors were reversed, whereas the motivational reduction was not clearly affected. Notably, the motivational reduction appeared obviously during the first week after the social defeat, and the conventional tricyclic antidepressant clomipramine did not reverse the reduced motivation.

CONCLUSIONS

These findings imply that motivational variation might be applied as a more sensitive behavioral index in subordinate animals and could furthermore be used to evaluate potential agents as antidepressants.

Long-Term Stress and Concomitant Marijuana Smoke Exposure Affect Physiology, Behavior and Adult Hippocampal Neurogenesis

Marijuana is a widely used recreational drug with increasing legalization worldwide for medical purposes. Most experimental studies use either synthetic or plant-derived cannabinoids to investigate the effect of cannabinoids on anxiety and cognitive functions. The aim of this study was to mimic real life situations where young people smoke cannabis regularly to relax from everyday stress. Therefore, we exposed young adult male NMRI mice to daily stress and concomitant marijuana smoke for 2 months and investigated the consequences on physiology, behavior and adult hippocampal neurogenesis. Animals were restrained for 6-h/day for 5-days a week. During the stress, mice were exposed to cannabis smoke for 2 × 30 min/day. We burned 2 “joints” (2 × 0.8 g marijuana) per occasion in a whole body smoking chamber. Cannabinoid content of the smoke and urine samples was measured by HPLC and SFC-MS/MS. Body weight gain was recorded daily and we did unrestrained, whole body plethysmography to investigate pulmonary functions. The cognitive performance of the animals was evaluated by the novel object recognition and Y maze tests. Anxietyrelated spontaneous locomotor activity and self-grooming were assessed in the open field test (OFT). Adult neurogenesis was quantified post mortem in the hippocampal dentate gyrus. The proliferative activity of the precursor cells was detected by the use of the exogenous marker 5-bromo-20-deoxyuridine. Treatment effects on maturing neurons were studied by the examination of doublecortin-positive neurons. Both stress and cannabis exposure significantly reduced body weight gain. Cannabis smoke had no effect on pulmonary functions, but stress delayed the maturation of several lung functions. Neither stress, nor cannabis smoke affected the cognitive functioning of the animals. Results of the OFT revealed that cannabis had a mild anxiolytic effect and markedly increased self-grooming behavior. Stress blocked cell proliferation in the dentate gyrus, but cannabis had no effect on this parameter. Marijuana smoke however had a pronounced impact on doublecortin-positive neurons influencing their number, morphology and migration. In summary, we report here that long-term stress in combination with cannabis smoke exposure can alter several health-related measures, but the present experimental design could not reveal any interaction between these two treatment factors except for body weight gain.

Absence of Stress Response in Dorsal Raphe Nucleus in Modulator of Apoptosis 1-Deficient Mice

Modulator of apoptosis 1 (MOAP-1) is a Bcl-2-associated X Protein (BAX)-associating protein that plays an important role in regulating apoptosis. It is highly enriched in the brain but its function in this organ remains unknown. Studies on BAX^-/- mice suggested that disruption of programmed cell death may lead to abnormal emotional states. We thus hypothesize that MOAP-1^-/- mice may also display stress-related behavioral differences and perhaps involved in stress responses in the brain and investigated if a depression-like trait exists in MOAP-1^-/- mice, and if so, whether it is age related, and how it relates to central serotonergic stress response in the dorsal raphe nucleus. Young MOAP-1^-/- mice exhibit depression-like behavior, in the form of increased immobility time when compared to age-matched wild-type mice in the forced swimming test, which is abolished by acute treatment of fluoxetine. This is supported by data from the tail suspension and sucrose preference tests. Repeated forced swimming stress causes an up-regulation of tryptophan hydroxylase 2 (TPH2) and a down-regulation of brain-derived neurotrophic factor (BDNF) in the dorsal raphe nucleus (DRN) in young wild-type (WT) control mice. In contrast, TPH2 up-regulation was not observed in aged WT mice. Interestingly, such a stress response appears absent in both young and aged MOAP-1^-/- mice. Aged MOAP-1^-/- and WT mice also have similar immobility times on the forced swimming test. These data suggest that MOAP-1 is required in the regulation of stress response in the DRN. Crosstalk between BDNF and 5-HT appears to play an important role in this stress response.

Adult Hippocampal Neurogenesis: Regulation and Possible Functional and Clinical Correlates

The formation of new neurons in the adult central nervous system (CNS) has been recognized as one of the major findings in neuroanatomical research. The hippocampal formation (HF), one of the main targets of these investigations, holds a neurogenic niche widely recognized among several mammalian species and whose existence in the human brain has sparked controversy and extensive debate. Many cellular features from this region emphasize that hippocampal neurogenesis suffers changes with normal aging and, among regulatory factors, physical exercise and chronic stress provoke opposite effects on cell proliferation, maturation and survival. Considering the numerous functions attributable to the HF, increasing or decreasing the integration of new neurons in the delicate neuronal network might be significant for modulation of cognition and emotion. The role that immature and mature adult-born neurons play in this circuitry is still mostly unknown but it could prove fundamental to understand hippocampal-dependent cognitive processes, the pathophysiology of depression, and the therapeutic effects of antidepressant medication in modulating behavior and mental health.

Effects of Tianeptine on Adult Rats Following Prenatal Stress

Objective

Exposing a pregnant female to stress during the critical period of embryonic fetal brain development increases the risk of psychiatric disorders in the offspring. The objective of this study was to investigate the effect of antidepressant tianeptine on prenatally stressed (PNS) rats.

Methods

In this study, a repeated variable stress paradigm was applied to pregnant rats during the last week of gestation. To investigate the effects of antidepressant tianeptine on PNS rats, behavioral and protein expression analyses were performed. Forced swim test, open field test, and social interaction test were performed to determine changes in PNS rats compared to non-stressed offspring. Haloperidol was used as a positive control as an antipsychotic drug based on previous studies.

Results

Behavioral changes were restored after treatment with tianeptine or haloperidol. Western blot and immunohistochemical analyses of the prefrontal cortex revealed downregulation of several neurodevelopmental proteins in PNS rats. After treatment with tianeptine or haloperidol, their expression levels were increased.

Conclusion

Downregulation of several proteins in PNS rats might have caused subsequent behavioral changes in PNS rats. After tianeptine or haloperidol treatment, behavioral changes in PNS rats were restored. Therefore, tianeptine might decrease incidence of prenatal stress related-psychiatric disorders such as depression and schizophrenia.

Zinc, Magnesium, Selenium and Depression: A Review of the Evidence, Potential Mechanisms and Implications

Micronutrient deficiency and depression are major global health problems. Here, we first review recent empirical evidence of the association between several micronutrients—zinc, magnesium, selenium—and depression. We then present potential mechanisms of action and discuss the clinical implications for each micronutrient. Collectively, empirical evidence most strongly supports a positive association between zinc deficiency and the risk of depression and an inverse association between zinc supplementation and depressive symptoms. Less evidence is available regarding the relationship between magnesium and selenium deficiency and depression, and studies have been inconclusive. Potential mechanisms of action involve the HPA axis, glutamate homeostasis and inflammatory pathways. Findings support the importance of adequate consumption of micronutrients in the promotion of mental health, and the most common dietary sources for zinc and other micronutrients are provided. Future research is needed to prospectively investigate the association between micronutrient levels and depression as well as the safety and efficacy of micronutrient supplementation as an adjunct treatment for depression.

Protective effects of Polygonum multiflorum on ischemic stroke rat model analysed by 1H NMR metabolic profiling

Stroke is the third most common cause of death in most industrialized countries. Polygonum multiflorum (He-Shou-Wu, HSW) is one of the traditional Chinese medicines with multiple pharmacological activities which is widely used in Chinese recipe. This study aims to explore the protective effect of HSW on ischemic stroke rat model and to elucidate the underlying mechanisms. The mortality rate, neurological deficit, cerebral infarct size, histopathology, immunohistochemistry, biochemical parameters, quantitative real-time polymerase chain reaction and western blotting were used to access the treatment effects of HSW on ischemic stroke. Proton nuclear magnetic resonance (¹H NMR) based metabolomics analysis disclosed that HSW could relieve stroke rats suffering from the ischemia/reperfusion injury by ameliorating the disturbed energy and amino acids metabolisms, alleviating the oxidative stress from reactive oxygen species and reducing the inflammation. HSW treatment increased levels of cellular antioxidants that scavenged reactive oxygen species during ischemia-reperfusion via the nuclear erythroid 2-related factor 2 signaling pathway, and exert anti-inflammatory effect by decreasing the levels of inflammatory factors such as cyclooxygenase-2, interleukin-1β, interleukin-6 and tumor necrosis factor-α. The integrated metabolomics approach showed its potential in understanding mechanisms of HSW in relieving ischemic stroke. Further study to develop HSW as an effective therapeutic agent to treat ischemic stroke is warranted.

Sex differences of hippocampal structure in bipolar disorder

Although differential patterns in clinical characteristics have been consistently noted between male and female patients with bipolar disorder (BD), the effect of sex on the hippocampal structure remains unclear. To address this, the present study investigated the effects of BD and sex on the hippocampal structure, and the relationship between the hippocampal structure and cognitive performance. Morphometric and neurocognitive analyses were performed in 91 subjects (patients with BD: male/female = 33/19; normal controls: male/female = 22/17). Patients had significantly decreased left parahippocampal gyrus area and left/right hippocampal volume compared to normal controls. Within the BD group only, female patients presented with smaller right hippocampal volume than males. In the Spatial Span (SS) test (used to assess working memory capacity) and the Maze test (used to evaluate the ability to anticipate), patients demonstrated decreased performance compared to normal controls, with a significant main effect of sex. Left parahippocampal gyrus area and right hippocampal volume were positively correlated with SS and Maze in patients; moreover, right hippocampal volume predicted 17.4% of SS performance variance. These results suggest that there may be a difference between male and female patients with regard to right hippocampal volume, and that female patients may need more attention than males.

WITHDRAWN: Non-infectious stressors and innate immune response

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Lateralized hippocampal volume increase following high-frequency left prefrontal repetitive transcranial magnetic stimulation in patients with major depression

AIM

Repetitive transcranial magnetic stimulation (rTMS) has been applied as a treatment for patients with treatment-resistant depression in recent years, and a large body of evidence has demonstrated its therapeutic efficacy through stimulating neuronal plasticity. The aim of this study was to investigate structural alterations in the hippocampus (HIPP) and amygdala (AM) following conventional rTMS in patients with depression.

METHODS

Twenty-eight patients with depression underwent 10 daily 20-Hz left prefrontal rTMS over 2 weeks. The left dorsolateral prefrontal cortex (DLPFC) was identified using magnetic resonance imaging-guided neuronavigation prior to stimulation. Magnetic resonance imaging scans were obtained at baseline and after the completion of rTMS sessions. The therapeutic effects of rTMS were evaluated with the 17-item Hamilton Depression Rating Scale (HAM-D₁₇ ), and the volumes of the HIPP and AM were measured by a manual tracing method.

RESULTS

Statistical analyses revealed a significant volume increase in the left HIPP (+3.4%) after rTMS but no significant volume change in the AM. No correlation was found between the left HIPP volume increase and clinical improvement, as measured by the HAM-D₁₇ .

CONCLUSION

The present study demonstrated that conventional left prefrontal rTMS increases the HIPP volume in the stimulated side, indicating a remote neuroplastic effect through the cingulum bundle.

Modulation of Adult Hippocampal Neurogenesis by Sleep: Impact on Mental Health

The process of neurogenesis has been demonstrated to occur throughout life in the subgranular zone (SGZ) of the hippocampal dentate gyrus of several mammals, including humans. The basal rate of adult hippocampal neurogenesis can be altered by lifestyle and environmental factors. In this perspective review, the evidence for sleep as a modulator of adult hippocampal neurogenesis is first summarized. Following this, the impacts of sleep and sleep disturbances on hippocampal-dependent functions, including learning and memory, and depression are critically evaluated. Finally, we postulate that the effects of sleep on hippocampal-dependent functions may possibly be mediated by a change in adult hippocampal neurogenesis. This could provide a route to new treatments for cognitive impairments and psychiatric disorders.

Hippocampal GABAergic Inhibitory Interneurons

In the hippocampus GABAergic local circuit inhibitory interneurons represent only ~10-15% of the total neuronal population; however, their remarkable anatomical and physiological diversity allows them to regulate virtually all aspects of cellular and circuit function. Here we provide an overview of the current state of the field of interneuron research, focusing largely on the hippocampus. We discuss recent advances related to the various cell types, including their development and maturation, expression of subtype-specific voltage- and ligand-gated channels, and their roles in network oscillations. We also discuss recent technological advances and approaches that have permitted high-resolution, subtype-specific examination of their roles in numerous neural circuit disorders and the emerging therapeutic strategies to ameliorate such pathophysiological conditions. The ultimate goal of this review is not only to provide a touchstone for the current state of the field, but to help pave the way for future research by highlighting where gaps in our knowledge exist and how a complete appreciation of their roles will aid in future therapeutic strategies.

Neuroprotective effect of amantadine on corticosterone-induced abnormal glutamatergic synaptic transmission of CA3-CA1 pathway in rat's hippocampal slices

Depression is a psychiatric disorder and chronic stress, leading to altered glucocorticoid secretion patterns, is one of the factors that induce depression. Our previous study showed that amantadine significantly attenuated the impairments of synaptic plasticity and cognitive function a rat model of CUS. However, little is known regarding the underlying mechanism. In the present study, the whole-cell patch-clamp technique was applied to examine the protection effect of amantadine on the hippocampus CA3-CA1 pathway. Evoked excitatory postsynaptic currents (eEPSCs), miniature excitatory postsynaptic currents (mEPSCs), paired-pulse ratio (PPR) and the action potentials of CA3 neurons were recorded. Our data showed that corticosterone increased the amplitude of eEPSCs and decreased the value of paired-pulse ratio (PPR), but both of them were significantly reversed by amantadine. In addition, the frequency of mEPSC was considerably increased by corticosterone, but it was reduced by amantadine. Moreover, we used the Fluo-3/AM image to detect the Ca²⁺ influx in primary cultured hippocampal neurons. The results showed that the intracellular calcium levels were significantly decreased by amantadine in the corticosterone treated neurons. Additionally, the superoxide dismutase (SOD) and catalase (CAT) activities were reduced by corticosterone, while they were enhanced by either amantadine or low-calcium artificial cerebral spinal fluid (ACSF). These results suggest that amantadine significantly improves corticosterone-induced abnormal glutamatergic synaptic transmission of CA3-CA1 synapses presynaptically and alleviates the activities of antioxidant enzymes via regulating the calcium influx.

Rosiglitazone Exerts an Anti-depressive Effect in Unpredictable Chronic Mild-Stress-Induced Depressive Mice by Maintaining Essential Neuron Autophagy and Inhibiting Excessive Astrocytic Apoptosis

There is increasing interest in the association between depression and the development of metabolic diseases. Rosiglitazone, a therapeutic drug used to treat type 2 diabetes mellitus, has shown neuroprotective effects in patients with stroke and Alzheimer's disease. The present study was performed to evaluate the possible roles of rosiglitazone in in vivo (unpredictable chronic mild stress-induced depressive mouse model) and in vitro (corticosterone-induced cellular model) depressive models. The results showed that rosiglitazone reversed depressive behaviors in mice, as indicated by the forced swimming test and open field test. Rosiglitazone was also found to inhibit the inflammatory response, decrease corticosterone levels, and promote astrocyte proliferation and neuronal axon plasticity in the prefrontal cortex of mice. This series of in vivo and in vitro experiments showed that autophagy among neurons was inhibited in depressive models and that rosiglitazone promoted autophagy by upregulating LKB1, which exerted neuroprotective effects. Rosiglitazone was also found to activate the Akt/CREB pathway by increasing IGF-1R expression and IGF-1 protein levels, thereby playing an anti-apoptotic role in astrocytes. Rosiglitazone's autophagy promotion and neuroprotective effects were found to be reversed by the PPARγ antagonist T0070907 in primary neurons and by PPARγ knockdown in an N2a cell line. In conclusion, we found that rosiglitazone protects both neurons and astrocytes in in vivo and in vitro depressive models, thereby playing an anti-depressive role. These findings suggest that PPARγ could be a new target in the development of anti-depressive drugs.

Hierarchical Status Predicts Behavioral Vulnerability and Nucleus Accumbens Metabolic Profile Following Chronic Social Defeat Stress

Extensive data highlight the existence of major differences in individuals' susceptibility to stress [1-4]. While genetic factors [5, 6] and exposure to early life stress [7, 8] are key components for such neurobehavioral diversity, intriguing observations revealed individual differences in response to stress in inbred mice [9-12]. This raised the possibility that other factors might be critical in stress vulnerability. A key challenge in the field is to identify non-invasively risk factors for vulnerability to stress. Here, we investigated whether behavioral factors, emerging from preexisting dominance hierarchies, could predict vulnerability to chronic stress [9, 13-16]. We applied a chronic social defeat stress (CSDS) model of depression in C57BL/6J mice to investigate the predictive power of hierarchical status to pinpoint which individuals will exhibit susceptibility to CSDS. Given that the high social status of dominant mice would be the one particularly challenged by CSDS, we predicted and found that dominant individuals were the ones showing a strong susceptibility profile as indicated by strong social avoidance following CSDS, while subordinate mice were not affected. Data from ¹H-NMR spectroscopy revealed that the metabolic profile in the nucleus accumbens (NAc) relates to social status and vulnerability to stress. Under basal conditions, subordinates show lower levels of energy-related metabolites compared to dominants. In subordinates, but not dominants, levels of these metabolites were increased after exposure to CSDS. To the best of our knowledge, this is the first study that identifies non-invasively the origin of behavioral risk factors predictive of stress-induced depression-like behaviors associated with metabolic changes.

Lack of Social Support Raises Stress Vulnerability in Rats with a History of Ancestral Stress

Stress is a primary risk factor for psychiatric disorders. However, it is not fully understood why some stressed individuals are more vulnerable to psychiatric disorders than others. Here, we investigated whether multigenerational ancestral stress produces phenotypes that are sensitive to depression-like symptoms in rats. We also examined whether social isolation reveals potentially latent sensitivity to depression-like behaviours. F4 female rats born to a lineage of stressed mothers (F0-F3) received stress in adulthood while housed in pairs or alone. Social isolation during stress induced cognitive and psychomotor retardation only in rats exposed to ancestral stress. Social isolation also hampered the resilience of the hypothalamic-pituitary-adrenal axis to chronic stress and reduced hippocampal volume and brain-derived neurotrophic factor (BDNF) expression. Thus, synergy between social isolation and stress may unmask a latent history of ancestral stress, and raises vulnerability to mental health conditions. The findings support the notion that social support critically promotes stress coping and resilience.

Noninvasive Evaluation of Cellular Proliferative Activity in Brain Neurogenic Regions in Rats under Depression and Treatment by Enhanced [18F]FLT-PET Imaging

Neural stem cells in two neurogenic regions, the subventricular zone and the subgranular zone (SGZ) of the hippocampal dentate gyrus, can divide and produce new neurons throughout life. Hippocampal neurogenesis is related to emotions, including depression/anxiety, and the therapeutic effects of antidepressants, as well as learning and memory. The establishment of in vivo imaging for proliferative activity of neural stem cells in the SGZ might be used to diagnose depression and to monitor the therapeutic efficacy of antidepressants. Positron emission tomography (PET) imaging with 3'-deoxy-3'-[(18)F]fluoro-l-thymidine ([(18)F]FLT) has been studied to allow visualization of proliferative activity in two neurogenic regions of adult mammals; however, the PET imaging has not been widely used because of lower accumulation of [(18)F]FLT, which does not allow quantitative assessment of the decline in cellular proliferative activity in the SGZ under the condition of depression. We report the establishment of an enhanced PET imaging method with [(18)F]FLT combined with probenecid, an inhibitor of drug transporters at the blood-brain barrier, which can allow the quantitative visualization of neurogenic activity in rats. Enhanced PET imaging allowed us to evaluate reduced cell proliferation in the SGZ of rats with corticosterone-induced depression, and further the recovery of proliferative activity in rats under treatment with antidepressants. This enhanced [(18)F]FLT-PET imaging technique with probenecid can be used to assess the dynamic alteration of neurogenic activity in the adult mammalian brain and may also provide a means for objective diagnosis of depression and monitoring of the therapeutic effect of antidepressant treatment.

SIGNIFICANCE STATEMENT

Adult hippocampal neurogenesis may play a role in major depression and antidepressant therapy. Establishment of in vivo imaging for hippocampal neurogenic activity may be useful to diagnose depression and monitor the therapeutic efficacy of antidepressants. Positron emission tomography (PET) imaging has been studied to allow visualization of neurogenic activity; however, PET imaging has not been widely used due to the lower accumulation of the PET tracer in the neurogenic regions. Here, we succeeded in establishing highly quantitative PET imaging for neurogenic activity in adult brain with an inhibitor for drug transporter. This enhanced PET imaging allowed evaluation of the decline of neurogenic activity in the hippocampus of rats with depression and the recovery of neurogenic activity by antidepressant treatment.

Prenatal stress potentiates febrile seizure and leads to long-lasting increase in cortisol blood levels in children under 2years old

Neurological disorders can be exacerbated in an offspring that is exposed to stress prenatally. This study is aimed to investigate the severity of febrile seizures (FS) in the offspring under 2years old that were prenatally stressed. In this study, 158 children below 2years old with FS were selected. Information about convulsion including seizure lasting, recurrence of seizure, age of the first seizure and type of FS was gathered. Blood samples were obtained from the offspring to measure the cortisol blood levels. Questionnaire was filled in to evaluate the perceived stress and exposure or non-exposure to major stresses during pregnancy. Results of this study showed that both high Perceived Stress Scores (PSS) during pregnancy and exposure to major stresses during pregnancy significantly increased seizure duration and seizure intensity. Also, the appearance of complex FS was significantly higher in prenatally stressed children than the unexposed ones. Further, cortisol blood levels were significantly higher in prenatally stressed subjects. It can be concluded that both higher PSS and/or exposure to major stresses during pregnancy potentiate FS parameters and lead to long lasting increase in cortisol blood levels in the offspring.

Effects of tianeptine on symptoms of fibromyalgia via BDNF signaling in a fibromyalgia animal model

Previous reports have suggested that physical and psychological stresses may trigger fibromyalgia (FM). Stress is an important risk factor in the development of depression and memory impairments. Antidepressants have been used to prevent stress-induced abnormal pain sensation. Among various antidepressants, tianeptine has been reported to be able to prevent neurodegeneration due to chronic stress and reverse decreases in hippocampal volume. To assess the possible effect of tianeptine on FM symptoms, we constructed a FM animal model induced by restraint stress with intermittent cold stress. All mice underwent nociceptive assays using electronic von Frey anesthesiometer and Hargreaves equipment. To assess the relationship between tianeptine and expression levels of brain-derived neurotrophic factor (BDNF), cAMP response element-binding protein (CREB), and phosphorylated cAMP response element-binding protein (p-CREB), western blotting and immunohistochemistry analyses were performed. In behavioral analysis, nociception tests showed that pain threshold was significantly decreased in the FM group compared to that in the control group. Western blot and immunohistochemical analyses of medial prefrontal cortex (mPFC) and hippocampus showed downregulation of BDNF and p-CREB proteins in the FM group compared to the control group. However, tianeptine recovered these changes in behavioral tests and protein level. Therefore, this FM animal model might be useful for investigating mechanisms linking BDNF-CREB pathway and pain. Our results suggest that tianeptine might potentially have therapeutic efficacy for FM.

Psychophysiological response in parachute jumps, the effect of experience and type of jump

We aimed to analyse the effect of experience and type of parachute jump on the psychophysiological responses of jumpers. We analysed blood oxygen saturation, heart rate, blood glucose, lactate and creatinkinase, leg strength, isometric hand strength, cortical arousal, specific fine motor skills, self-confidence and cognition, and somatic and state anxiety, before and after four different parachute jumps: a sport parachute jump, a manual tactical parachute jump, tandem pilots, and tandem passengers. Independently of the parachute jump, the psychophysiological responses of experienced paratroopers were not affected by the jumps, except for an increase in anaerobic metabolism. Novice parachute jumpers presented a higher psychophysiological stress response than the experienced jumpers, together with a large anticipatory anxiety response before the jump; however, this decreased after the jump, although the high physiological activation was maintained. This information could be used by civil and military paratroopers' instructors to improve their training programmes.

Viral-mediated overexpression of the Myelin Transcription Factor 1 (MyT1) in the dentate gyrus attenuates anxiety- and ethanol-related behaviors in rats

RATIONALE

Myelin Transcription Factor 1 (MyT1), a member of the Zinc Finger gene family, plays a fundamental role in the nervous system. Recent research has suggested that this transcription factor is associated with the pathophysiology of psychiatric disorders including addiction, schizophrenia, and depression. However, the role of MyT1 in anxiety- and ethanol-related behaviors is still unknown.

OBJECTIVES

We evaluated the effects of lentiviral-mediated overexpression of MyT1 in the dentate gyrus (DG) on anxiety- and ethanol-related behaviors in rats.

METHODS

We used the elevated plus maze (EPM) and the open field (OF) tests to assess anxiety-like behavior and a two-bottle choice procedure to measure the effects of MyT1 on ethanol intake and preference.

RESULTS

MyT1 overexpression produced anxiolytic-like effects in the EPM test and decreased the number of fecal boli in the OF test, without affecting locomotor activity in both behavioral tests. Next, we demonstrated that ethanol intake and preference were decreased in the MyT1-overexpressing rats with no effect on saccharin and quinine, used to assess taste discrimination, and no effect on ethanol clearance suggesting specific alterations in the rewarding effects of ethanol. Most importantly, ectopic MyT1 overexpression increased both MyT1 and BDNF mRNA levels in the DG. Using Pearson's correlation, results showed a strong negative relationship between MyT1 mRNA and anxiety parameters and ethanol consumption and a positive correlation between MyT1 and BDNF mRNAs.

CONCLUSION

Taken together, MyT1 along with being a key component in anxiety may be a suitable candidate in the search of the molecular underpinnings of alcoholism.

Effects of [Nphe1, Arg14, Lys15] N/OFQ-NH2 (UFP-101), a potent NOP receptor antagonist, on molecular, cellular and behavioural alterations associated with chronic mild stress

The present study investigated the effect of [Nphe¹] Arg¹⁴, Lys¹⁵-N/OFQ-NH₂ (UFP-101), a selective NOP receptor antagonist, in chronic mild stress (CMS) in male Wistar rats. NOP receptor antagonists were reported to elicit antidepressant-like effects in rodents. Our aim was to investigate UFP-101 effects on CMS-induced anhedonia and impairment of hippocampal neurogenesis. UFP-101 (10 nmol/rat intracerebroventricularly) did not influence sucrose intake in non-stressed animals, but reinstated basal sucrose consumption in stressed animals from the second week of treatment. UFP-101 also reversed stress effects in forced swimming test and in open field. Fluoxetine (10 mg/kg intraperitoneally) produced similar effects. Moreover, we investigated whether UFP-101 could affect CMS-induced impairment in hippocampal cell proliferation and neurogenesis, and in fibroblast growth factor (FGF-2) expression. Our data confirm that CMS reduced neural stem cell proliferation and neurogenesis in adult rat hippocampus. Chronic UFP-101 treatment did not affect the reduced proliferation (bromodeoxyuridine-positive cells) observed in stressed animals. However, UFP-101 increased the number of doublecortin-positive cells, restoring neurogenesis. Finally, UFP-101 significantly increased FGF-2 expression, reduced by CMS. These findings support the view that blockade of NOP receptors produces antidepressant-like effects in CMS associated with positive effects on neurogenesis and FGF-2 expression. Therefore, NOP receptors may represent a target for innovative antidepressant drugs.

Advanced Parental Age Impaired Fear Conditioning and Hippocampal LTD in Adult Female Rat Offspring

Advanced maternal or paternal age is associated with increased risks of cognitive and emotional disorders. Chronic stress is also a common experience in human life that causes psychiatric diseases. However, the synergistic effects of these two factors on offspring are rarely studied. In the present study, the offspring of both young (3-4 months) and old (12-14 months) rat parents were given CUMS for 21 days at the age of 4 weeks. The effects of advanced parental age and chronic unpredictable mild stress (CUMS) on emotional and cognitive behaviors and the related cellular mechanisms were investigated by using behavioral and electrophysiological techniques. We found that CUMS decreased sucrose consumption, increased anxiety, and impaired learning and memory in offspring from both old and young breeders. However, advanced parental age impaired fear memory and spatial memory mainly in female offspring. The serum corticosterone of female offspring was lower than males, but advanced parental age significantly elevated serum corticosterone in female offspring in response to electrical foot shocks. In addition, hippocampal LTD was severely impaired in female offspring from older parents. Our results indicated that female offspring from older breeders might be more sensitive to stress, and the hippocampal function was more vulnerable. These results might provide experimental basis for the prevention and treatment of advanced parental age related psychiatric disorders in future.

Effect of Combat Stress in the Psychophysiological Response of Elite and Non-Elite Soldiers

We aimed to analyse the effect of combat stress in the psychophysiological responses of elite and non-elite soldiers. We analysed heart rate, cortical arousal, skin temperature, blood lactate concentration and lower body muscular strength before and after a tactical combat simulation in 40 warfighters divided in two groups: elite (n: 20; 28.5 ± 6.38 years) and non-elite (n:20; 31.94 ± 6.24 years) group. Elite presented a significantly higher lactate concentration after combat than non elite soldiers (3.8 ± 1.5 vs 6.6 ± 1.3 mmol/L). Non-elite soldiers had a higher heart rate pre and post the simulation than elite (82.9 ± 12.3 vs 64.4 ± 11. pre non elite and elite respectively; 93.0 ± 12.8 vs 88 ± 13.8 bpm post non elite and elite respectively). Elite soldiers presented higher lower muscular strength than elite in all test and before and after the combat simulation. Cortical arousal was not modified significantly in both groups. We conclude elite soldiers presented in combat a higher anaerobic metabolism activation and muscular strength than non-elite soldiers, but cardiovascular, cortical, and muscular strength manifestation presented the same response in both elite and non-elite soldiers.

Hippocampal neurogenesis of Wistar Kyoto rats is congenitally impaired and correlated with stress resistance

The hippocampus is thought to be an important region for depression. However, the relationship between hippocampal neurogenesis and depression is still controversial. Wistar Kyoto (WKY) rats are frequently used as a depression model. WKY rats are known to show physiologically abnormal features, and these features resemble abnormalities seen in depressed patients. However, the neurogenesis of WKY rats is still unknown. In this study, we first evaluated the neurogenesis of WKY rats and compared it to that of Wistar (WIS) rats. No strain effect was observed in the number of cells positive for 5-bromo-2'-deoxyuridine (BrdU) and BrdU/Doublecortin (Dcx) in the subventricular zone (SVZ). However, the number of BrdU- and BrdU/Dcx-positive cells in the dentate gyrus (DG) of the hippocampus was significantly lower in WKY rats than in WIS rats. Next, we evaluated the correlation between neurogenesis and behavior tests. Behavior tests did not affect neurogenesis in either strain. Hippocampal neurogenesis correlated negatively with the results of a forced swim test (FST) on day 2 in each strain. That is, rats with a lower level of native neurogenesis in the DG showed a higher level of learned helplessness induced by the inescapable stress of the FST on day 1. Our findings indicate that hippocampal neurogenesis in WKY rats is congenitally impaired in contrast to that in WIS rats. Native cell proliferation and neurogenesis in the DG are correlated with stress resistance. These findings may be useful for developing new targets for depression treatment.

White matter atrophy and myelinated fiber disruption in a rat model of depression

Brain imaging and postmortem studies have indicated that white matter abnormalities may contribute to the pathology and pathogenesis of depression. However, until now, no study has quantitatively investigated white matter changes in depression in rats. The current study used the chronic unpredictable stress (CUS) model of depression. Body weight and sucrose preference test (SPT) scores were assessed weekly. Upon successfully establishing the CUS animal model, all animals were tested using the SPT and the open field test (OFT). Then, transmission electron microscopy and unbiased stereological methods were used to investigate white matter changes in the rats. Compared with the control group, the body weight and sucrose preference of the CUS rats were significantly decreased (p < .001, p < .001, respectively). In the OFT, the total time spent and the total distance traveled in the inner area by the CUS rats were significantly lower than those of the control group (p = .002, p = .001, respectively). The stereological results revealed that white matter volume, the total volume, and the total length and mean diameter of myelinated fibers in the white matter of the CUS rats were significantly decreased compared to the control rats (p = .042, p = .038, p = .035, p = .019, respectively). The results of this study suggested that white matter atrophy and disruption of myelinated fibers in the white matter may contribute to the pathophysiology underlying depression, which might provide new targets for the development of novel therapeutic interventions for depression.

Involvement of Normalized Glial Fibrillary Acidic Protein Expression in the Hippocampi in Antidepressant-Like Effects of Xiaoyaosan on Chronically Stressed Mice

The research has only yielded a partial comprehension of MDD and the mechanisms underlying the antidepressant-like effects of XYS. Therefore, in this study, we aimed to explore the effects of XYS on chronic unpredictable mild stress- (CUMS-) induced changes in the neuronal and the astrocytic markers in the mouse hippocampus. The physical states and depressive-like behaviors in mice with CUMS were recorded. The serum contents of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) were measured. The protein and mRNA expressions and the immunoreactivities of glial fibrillary acidic protein (GFAP) and neuronal nuclei (NeuN) in mouse hippocampus were detected using a Western blot, qRT-PCR, and immunohistochemical staining, respectively. XYS treatment markedly improved the physical state and depressive-like behaviors in mice subjected to CUMS compared with the model group, and the serum contents of BDNF and GDNF were significantly upregulated. XYS treatment also elevated the protein and mRNA levels, as well as the immunoreactivity of GFAP in the hippocampus. However, CUMS did not influence NeuN expression. In conclusion, these results reveal that chronic administration of XYS elicits antidepressant-like effects in a mouse model of depression and may normalize glial fibrillary acidic protein expression in the hippocampi of mice with CUMS.