Effects of chronic restraint stress on feeding behavior and on monoamine levels in different brain structures in rats

Sex-specific expression of distinct serotonin receptors mediates stress vulnerability of adult hippocampal neural stem cells in mice

Women are more vulnerable to stress and have a higher likelihood of developing mood disorders. The serotonin (5HT) system has been highly implicated in stress response and mood regulation. However, sex-dependent mechanisms underlying serotonergic regulation of stress vulnerability remain poorly understood. Here, we report that adult hippocampal neural stem cells (NSCs) of the Ascl1 lineage (Ascl1-NSCs) in female mice express functional 5HT1A receptors (5HT1ARs), and selective deletion of 5HT1ARs in Ascl1-NSCs decreases the Ascl1-NSC pool only in females. Mechanistically, 5HT1AR deletion in Ascl1-NSCs of females leads to 5HT-induced depolarization mediated by upregulation of 5HT7Rs. Furthermore, repeated restraint stress (RRS) impairs Ascl1-NSC maintenance through a 5HT1AR-mediated mechanism. By contrast, Ascl1-NSCs in males express 5HT7R receptors (5HT7Rs) that are downregulated by RRS, thus maintaining the Ascl1-NSC pool. These findings suggest that sex-specific expression of distinct 5HTRs and their differential interactions with stress may underlie sex differences in stress vulnerability.

The Antidepressant Activity of a Taurine-Containing Derivative of 4-Phenylpyrrolidone-2 in a Model of Chronic Unpredictable Mild Stress

This study investigates the therapeutic potential of a new compound, potassium 2-[2-(2-oxo-4-phenylpyrrolidin-1-yl) acetamido]ethanesulfonate (Compound I), in depression. Willner's chronic unpredictable mild stress model of male Wistar rats was used as a depression model. The rats were randomized into four groups, including an intact group, a Compound I group, a Fluoxetine group, and a control group with saline. Behavioral tests, such as the Porsolt forced swim test, hole-board test, elevated plus maze test, and light-dark box, were used to assess the animals' conditions. Our results demonstrated that Compound I effectively reduced the immobilization time of rats in the forced swim test, increased orientation and exploratory behavior, and decreased the latency period of going into the dark compartment compared to the control group. Hippocampal and striatal serotonin concentrations were increased in the Compound I group, and the compound also reduced the level of corticosterone in the blood plasma of rats compared to the intact animals. These results suggest that Compound I has reliable antidepressant activity, comparable to that of the reference antidepressant Fluoxetine.

Treadmill Exercise Improves Behavioral and Neurobiological Alterations in Restraint-Stressed Rats

Stress is a state that is known to impact an organism's physiological and psychological balance as well as the morphology and functionality of certain brain areas. In the present work, chronic restraint stress (CRS) model rats treated with treadmill exercise were used to examine anomalies associated to emotion and mood as well as molecular changes in the brain. Forty male Sprague-Dawley rats were divided into control, stress, exercise, and stress+exercise groups. CRS were exposed to stress group rats and exercise group underwent a chronic treadmill exercise. Depressive-like behavior was evaluated with the forced swim test (FST) and tail suspension test (TST). For assessing anxiety-like behavior, the light-dark test (LDT) and the open field test (OFT) were used. The Morris water maze test (MWMT) was used for testing memory and learning. Brain's monoamine level and the expression of genes related to stress were measured. It was discovered that CRS lengthens latency in the MWMT, increases immobility in the FST and TST, decreases time in the light compartment, and causes hypoactivity in the OFT. CRS reduced the dopamine levels in the nucleus accumbens(NAc). Brain-derived neurotrophic factor (BDNF), dopamine receptors, and serotonin receptor (HTR2A) gene expression in the prefrontal cortex, corpus striatum, and hypothalamus were decreased by CRS. Exercise on a treadmill leads to increase NAc's dopamine and noradrenaline levels and prevented behavioral alterations. Exercise increased the alterations of BDNF expressions in the brain in addition to improving behavior. As a result, CRS-induced behavioral impairments were effectively reversed by chronic treadmill exercise with molecular alterations in the brain.

Nanowired delivery of dl-3-n-butylphthalide with antibodies to alpha synuclein potentiated neuroprotection in Parkinson's disease with emotional stress

Stress is one of the most serious consequences of life leading to several chronic diseases and neurodegeneration. Recent studies show that emotional stress and other kinds of anxiety and depression adversely affects Parkinson's disease symptoms. However, the details of how stress affects Parkinson's disease is still not well known. Traumatic brain injury, stroke, diabetes, post-traumatic stress disorders are well known to modify the disease precipitation, progression and persistence. However, show stress could influence Parkinson's disease is still not well known. The present investigation we examine the role of immobilization stress influencing Parkinson's disease brain pathology in model experiments. In ore previous report we found that mild traumatic brain injury exacerbate Parkinson's disease brain pathology and nanodelivery of dl-3-n-butylphthalide either alone or together with mesenchymal stem cells significantly attenuated Parkinson's disease brain pathology. In this chapter we discuss the role of stress in exacerbating Parkinson's disease pathology and nanowired delivery of dl-3-n-butylphthalide together with monoclonal antibodies to alpha synuclein (ASNC) is able to induce significant neuroprotection. The possible mechanisms of dl-3-n-butylphthalide and ASNC induced neuroprotection and suitable clinical therapeutic strategy is discussed.

Prelimbic Cortical Stimulation Induces Antidepressant-like Responses through Dopaminergic-Dependent and -Independent Mechanisms

High-frequency stimulation (HFS) is a promising therapy for patients with depression. However, the mechanisms underlying the HFS-induced antidepressant-like effects on susceptibility and resilience to depressive-like behaviors remain obscure. Given that dopaminergic neurotransmission has been found to be disrupted in depression, we investigated the dopamine(DA)-dependent mechanism of the antidepressant-like effects of HFS of the prelimbic cortex (HFS PrL). We performed HFS PrL in a rat model of mild chronic unpredictable stress (CUS) together with 6-hydroxydopamine lesioning in the dorsal raphe nucleus (DRN) and ventral tegmental area (VTA). Animals were assessed for anxiety, anhedonia, and behavioral despair. We also examined levels of corticosterone, hippocampal neurotransmitters, neuroplasticity-related proteins, and morphological changes in dopaminergic neurons. We found 54.3% of CUS animals exhibited decreased sucrose consumption and were designated as CUS-susceptible, while the others were designated CUS-resilient. HFS PrL in both the CUS-susceptible and CUS-resilient animals significantly increased hedonia, reduced anxiety, decreased forced swim immobility, enhanced hippocampal DA and serotonin levels, and reduced corticosterone levels when compared with the respective sham groups. The hedonic-like effects were abolished in both DRN- and VTA-lesioned groups, suggesting the effects of HFS PrL are DA-dependent. Interestingly, VTA-lesioned sham animals had increased anxiety and forced swim immobility, which was reversed by HFS PrL. The VTA-lesioned HFS PrL animals also had elevated DA levels, and reduced p-p38 MAPK and NF-κB levels when compared to VTA-lesioned sham animals. These findings suggest that HFS PrL in stressed animals leads to profound antidepressant-like responses possibly through both DA-dependent and -independent mechanisms.

Potential of Capric Acid in Neurological Disorders: An Overview

To solve the restrictions of a classical ketogenic diet, a modified medium-chain triglyceride diet was introduced which required only around 60% of dietary energy. Capric acid (CA), a small molecule, is one of the main components because its metabolic profile offers itself as an alternate source of energy to the brain in the form of ketone bodies. This is possible with the combined capability of CA to cross the blood-brain barrier and achieve a concentration of 50% concentration in the brain more than any other fatty acid in plasma. Natural sources of CA include vegetable oils such as palm oil and coconut oil, mammalian milk and some seeds. Several studies have shown that CA has varied action on targets that include AMPA receptors, PPAR-γ, inflammatory/oxidative stress pathways and gut dysbiosis. Based on these lines of evidence, CA has proved to be effective in the amelioration of neurological diseases such as epilepsy, affective disorders and Alzheimer's disease. But these studies still warrant more pre-clinical and clinical studies that would further prove its efficacy. Hence, to understand the potential of CA in brain disease and associated comorbid conditions, an advance and rigorous molecular mechanistic study, apart from the reported in-vitro/in-vivo studies, is urgently required for the development of this compound through clinical setups.

Sex differences in cognition following variations in endocrine status

Spatial memory, mediated primarily by the hippocampus, is responsible for orientation in space and retrieval of information regarding location of objects and places in an animal's environment. Since the hippocampus is dense with steroid hormone receptors and is capable of robust neuroplasticity, it is not surprising that changes in spatial memory performance occur following a variety of endocrine alterations. Here, we review cognitive changes in both spatial and nonspatial memory tasks following manipulations of the hypothalamic-pituitary-adrenal and gonadal axes and after exposure to endocrine disruptors in rodents. Chronic stress impairs male performance on numerous behavioral cognitive tasks and enhances or does not impact female cognitive function. Sex-dependent changes in cognition following stress are influenced by both organizational and activational effects of estrogen and vary depending on the developmental age of the stress exposure, but responses to gonadal hormones in adulthood are more similar than different in the sexes. Also discussed are possible underlying neural mechanisms for these steroid hormone-dependent, cognitive effects. Bisphenol A (BPA), an endocrine disruptor, given at low levels during adolescent development, impairs spatial memory in adolescent male and female rats and object recognition memory in adulthood. BPA's negative effects on memory may be mediated through alterations in dendritic spine density in areas that mediate these cognitive tasks. In summary, this review discusses the evidence that endocrine status of an animal (presence or absence of stress hormones, gonadal hormones, or endocrine disruptors) impacts cognitive function and, at times, in a sex-specific manner.

Anxiolytic and antidepressant-like activities of aqueous extract of Azadirachta indica A. Juss. flower in the stressed rats

The aim of this study was to evaluate whether an aqueous extract of Azadirachta indica A. Juss. (A. indica) flower had anxiolytic and antidepressant-like effects in the stressed rats. Male Wistar rats were randomly allocated to one of two experimental groups: control or stress. The stress groups were received restraint stress for 3 h. The stressed rats were administered a vehicle, diazepam, fluoxetine, and A. indica at doses of 250, 500, and 1000 mg/kg BW for 30 days. The elevated plus-maze test (EPMT), the forced swimming test (FST), and the open field test (OFT) were used to assess anxiolytic and antidepressant-like behaviors. In the EPMT, the percentage of the number of open arm entries and the duration spent in open arms were measured. These measurements were considerably enhanced in the stressed rats treated with diazepam and A. indica flower extract at a dose of 500 mg/kg BW. Furthermore, the stressed rats given fluoxetine and A. indica flower extract at all doses employed in this study showed a significant reduction in the amount of time the rats were immobilized in the FST. However, there was no significant difference in spontaneous locomotor activity between any of the groups. Additionally, the stressed rats treated with either positive control medications or A. indica flower extract exhibited significantly higher brain dopamine (DA) and serotonin (5-HT) levels, but lower blood cortisol levels as compared to the stressed rats treated with vehicle. Moreover, A. indica flower extract had no harmful effect on the stressed rats’ liver tissue.

A Comparison Study of Chaihu Shugan San and Fluoxetine on Antidepression and Regulating Blood Rheology Effects with Chronic Restrained Stress Rats

Chaihu Shugan San (CHSGS) is a traditional Chinese herbal formula that is often used in clinical practice to treat live Qi stagnation syndrome and depression. Fluoxetine is one of the commonly used drugs for the clinical treatment of depression. This study involved a comparison of CHSGS and fluoxetine on antidepression and regulating blood rheology effects with chronic restraint stress- (CRS-) induced depression rat models. Rats were induced depression models by CRS for 4 weeks. Upon successful induction of depression in the rats, the animal was administered CHSGS at 0.6 g/kg/d, 1.2 g/kg/d, or fluoxetine 1.8 mg/kg/d to corresponding groups by gavage for 2 weeks. The changes of CRS rats were determined by behavior observations and sucrose preference test and hypothalamic-pituitary-adrenal cortex (HPA) axis functional status. The changes in monoamine neurotransmitters and related indicators of blood status were detected by enzyme-linked immunosorbent assay (ELISA), blood rheometer, and other methods. The outcome shows that CHSGS is superior to fluoxetine in regulating the appearance and HPA axis function of model rats. In addition, CHSGS and fluoxetine have similar effects in improving blood rheology, and both can alleviate the hypercoagulable state of blood via the platelet 5-hydroxytryptamine receptor 2A (5-HT2A) pathway in rats of depression. It was also observed that CHSGS can improve the blood state of depressed rats by restoring liver coagulation-anticoagulation balance and endothelium-related functions.

Anxiolytic activity of Psidium guajava in mice subjected to chronic restraint stress and effect on neurotransmitters in brain

The anxiolytic activity of Psidium guajava L. leaf ethanolic extract (PLE) and its effect on neurotransmitter systems was investigated. PLE, extracted using Soxhlet apparatus, was subjected to preliminary qualitative and quantitative (flavonoids and phenols) analyses. The anxiolytic activity at 100, 200, and 400 mg/Kg doses were assessed in mice using elevated plus maze (EPM) and light/dark transition (LDT) test models on days 1 and 16. Neurotransmitters such as monoamines (serotonin, norepinephrine, and dopamine), γ-aminobutyric acid (GABA), and glutamate were estimated in different regions of the brain (cortex, hippocampus, and cerebellum and brain stem). Phytoconstituents identified using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry were analyzed in silico to evaluate their potential binding mode(s) to GABA_A and 5-HT_1A receptors. Phytochemical studies showed the presence of alkaloids, tannins, flavonoids, saponins, anthraquinone glycosides, carbohydrates, and proteins, whereas total flavonoid and phenol contents were estimated to be 64.96 ± 0.95 and 206.58 ± 1.60 mg/g of dried extract, respectively. PLE treatment significantly enhanced exploratory activity of mice in EPM and LDT models with significant effects on monoamines, GABA and glutamate levels in the brain. The in silico studies suggested the interaction(s) of PLE component(s) with GABA_A /5-HT_1A receptors as a potential mechanism of its anxiolytic activity.

The Behavioral and Neurochemical Aspects of the Interaction between Antidepressants and Unpredictable Chronic Mild Stress

The behavioral and neurochemical effects of amitriptyline (10 mg/kg, i.p.) and fluoxetine (20 mg/kg, i.p.) after single and chronic administration in the setting of unpredictable mild stress in outbred ICR (CD-1) mice were studied. After a 28-day exposure to stress, we observed an increase in depressive reaction in a forced swim test in mice, as well as reduced hippocampal levels of serotonin (5-hydroxytryptamine, 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) and an increased hypothalamic level of noradrenaline (NA). Single and chronic administration of amitriptyline and fluoxetine shortened the immobility period and increased the time corresponding to active swimming in the forced swim test. The antidepressant-like effect of fluoxetine - but not of amitriptyline - after a single injection coincided with an increase in the 5-HT turnover in the hippocampus. Chronic administration of the antidepressants increased the hypothalamic levels of NA. Thus, the antidepressant- like effect of amitriptyline and fluoxetine may result from an enhancement of the stress-dependent adaptive mechanisms depleted by chronic stress.

Impact of space allowance on performance traits, brain neurotransmitters and blood antioxidant activity of New Zealand White rabbits

The objective of this trial was to investigate the effect of space allowance on performance, welfare-related parameters and the levels of brain neurotransmitters in growing male rabbits. In a cage housing system, a total of 96 weaned rabbits were accommodated on three space allowance conditions (S₁ = 1425 cm²/rabbit; S₂ = 850 cm²/rabbit; S₃ = 625 cm²/rabbit), with 8 replicate cages per each group. Rabbits in the S₁ and S₂ groups showed better daily feed intake and feed conversion ratio compared with the high stocking density group (p = 0.004 and 0.018, respectively). Compared to the highest stocking density group (S₃), rabbits in the S₁ and S₂ groups showed significantly lower serum cortisol, MDA and GSSH level (p = 0.026, 0.018 and 0.009, respectively). The concentration of dopamine in brain tissues was significantly decreased in the S₃ group compared with other experimental groups (P = 0.001). However, there was no significant effect of space allowance on the brain AChE level (P = 0.277). Brain serotonin and GABA levels showed a significant decrease in rabbits reared with a limited space allowance (S₃) compared with S₁ and S₂ groups (P = 0.001 and 0.038, respectively). The level of brain MDA was significantly increased in the S₃ group compared with the S₁ group (P = 0.006). However, there were no detectable differences in the brain ATP level in rabbits reared with different space allowance (P = 0.693). In conclusion, the current study indicates that the 850 cm²/rabbit stocking density has resulted in a better feed intake, and welfare-related conditions compared with the 625 cm²/rabbit. Furthermore, the limited space allowance may impair the most important brain neurotransmitters in male rabbits.

Effects of Isolation and Social Subchronic Stresses on Food Intake and Levels of Leptin, Ghrelin, and Glucose in Male Rats

Background:

Exposure to psychological stresses can be a reason for obesity. Therefore, identifying the effective nutritional mechanisms such as feeding markers is of high necessity for the psychological stress conditions. Hence, the present study investigates the effects of subchronic isolation and social stresses on food intake, body weight differences (BWD), and levels of leptin, ghrelin, and glucose in rats.

Materials and Methods:

Eighteen male rats were randomly allocated into three groups: control (Co), isolation stress (IS), and social stress (SS) groups. Rats were under stresses for 7 days. The food intake (for three continuous hours after 16–18 h of food deprivation), BWD, levels of ghrelin, leptin, and glucose were measured.

Results:

The results showed that the food intake significantly (P < 0.05) reduced during the 1^st h in the SS group compared to the Co group. At the 2^nd h, the food intake significantly (P < 0.001 and P < 0.01, respectively) decreased in the IS group compared to the Co and SS groups. The cumulative food intake and body weight were significantly (P < 0.05) reduced in the IS group compared to the Co group. The serum ghrelin level significantly reduced in the IS group compared to the Co group.

Conclusions:

The subchronic psychological stresses led to a reduction in food intake by the reduction of serum ghrelin levels. It seems that ghrelin might have a more fundamental role in the food intake with respect to the leptin and glucose levels in subchronic stress condition. Furthermore, the decreased body weight justified the reduction of food intake, particularly in subchronic isolation stress.

Evaluation of antidepressant activity of methanolic extract of Saraca asoca bark in a chronic unpredictable mild stress model

It is well established that chronic exposure to stressful events plays an important role in the etiology of depression. Saraca asoca (Roxb.), De. wild, or Saraca indica, belonging to family Fabaceae, is endogenous to India. The flowers, seeds, bark, and leaves of the plant have been used widely in Ayurveda medicine. The bark extract of S. asoca has shown chemoprotection, myeloprotection, and antioxidant potential. Owing to the above-mentioned properties of the plant, the present study sought to evaluate the effect of a methanolic extract of S. asoca bark in rats exposed to chronic unpredictable mild stress (CUMS) daily for 8 weeks using a forced-swim test, an open-field test, and a sucrose-preference test. The effect of the extract on endogenous antioxidant levels in the brain was also assessed using catalase activity, superoxide dismutase activity, reduced glutathione levels, and malondialdehyde levels in the brain. Male Sprague-Dawley rats received 100 mg/kg (oral) of the extract daily 1 h before daily stress exposure for 8 weeks. The extract showed a significant reduction in the immobility time in the forced-swim test, increased the total number of line crossing, rearing, and grooming in the open-field test, and increased the sucrose consumption as well as the levels of endogenous antioxidants significantly in comparison with the CUMS control group. Therefore, S. asoca might be a useful agent for the treatment or alleviation of symptoms associated with depression possibly by reducing CUMS-induced oxidative stress and reactive oxygen species in the brain.

Dysfunction of Serotonergic and Dopaminergic Neuronal Systems in the Antidepressant-Resistant Impairment of Social Behaviors Induced by Social Defeat Stress Exposure as Juveniles

BACKGROUND

Extensive studies have been performed on the role of monoaminergic neuronal systems in rodents exposed to social defeat stress as adults. In the present study, we investigated the role of monoaminergic neuronal systems in the impairment of social behaviors induced by social defeat stress exposure as juveniles.

METHODS

Juvenile, male C57BL/6J mice were exposed to social defeat stress for 10 consecutive days. From 1 day after the last stress exposure, desipramine, sertraline, and aripiprazole were administered for 15 days. Social behaviors were assessed at 1 and 15 days after the last stress exposure. Monoamine turnover was determined in specific regions of the brain in the mice exposed to the stress.

RESULTS

Stress exposure as juveniles induced the impairment of social behaviors in adolescent mice. In mice that showed impairment of social behaviors, turnover of serotonin and dopamine, but not noradrenaline, was decreased in specific brain regions. Acute and repeated administration of desipramine, sertraline, and aripiprazole failed to attenuate the impairment of social behaviors, whereas repeated administration of a combination of sertraline and aripiprazole showed additive attenuating effects.

CONCLUSIONS

These findings suggest that social defeat stress exposure as juveniles induces the treatment-resistant impairment of social behaviors in adolescents through dysfunction in the serotonergic and dopaminergic neuronal systems. The combination of sertraline and aripiprazole may be used as a new treatment strategy for treatment-resistant stress-related psychiatric disorders in adolescents with adverse juvenile experiences.

Unfolded protein response and associated alterations in toll-like receptor expression and interaction in the hippocampus of restraint rats

Recent evidence suggests that the cellular response to stress often elicits the unfolded protein response (UPR), which has an active role in major depression in emotionally relevant regions of the brain, such as the hippocampus. Much of the UPR activity has been found to be coalesced with the pro-inflammatory environment of the depressed brain. Specifically, downstream transcriptions of pro-inflammatory cytokines and increased regulation of candidate inflammatory mediators, such as toll-like receptors (TLRs), are promoted by the UPR. The present study examined the hippocampus associated expression profile of Tlr genes and their interaction with the UPR chaperone GRP94 in stress-induced rodent model of depression (restraint stress model). Also, the expression status of UPR related genes was evaluated in hippocampus using the same model. mRNA and protein levels of Tlr and UPR associated genes were examined by qRT-PCR and Western blot, respectively. Co-immunoprecipitation (Co-IP) method was used to determine the direct interaction between TLRs with GRP94 in depressed rat brain. The results showed that both UPR (Xbp-1, its spliced variant sXbp-1, Atf-6, Chop, and Grp94) and Tlr (2, 3, 4, 7 and 9) genes were significantly upregulated in the hippocampi of rats who were exposed to restraint stress. Similar upregulation was observed in the protein levels of the above-mentioned TLRs and the UPR chaperone protein GRP94 as well as total and phosphorylated forms of sensor proteins IRE1α and PERK. Further, a significantly increased interaction was observed between GRP94 and the activated TLR proteins. Since, increased inflammatory activity in vulnerable areas like hippocampus is coherently associated with depressed brain; our present data suggest that the UPR may be an integral part of increased activity of inflammatory regulations in depression.

Exogenous daytime melatonin modulates response of adolescent mice in a repeated unpredictable stress paradigm

The immediate and short-term behavioural and physiological implications of exposure to stressful scenarios in the adolescent period are largely unknown; however, increases in occurrence of stress-related physiological and psychological disorders during puberty highlight the need to study substances that may modulate stress reactivity during a crucial stage of maturation. Seven groups of mice (12-15 g each) were administered distilled water (DW) (non-stressed and stressed controls), sertraline (10 mg/kg), diazepam (2 mg/kg) or one of three doses of melatonin (5, 10 and 15 mg/kg). Mice were exposed to 30 min of chronic mild stress (25 min of cage shaking, cage tilting, handling and 5 min of forced swimming in tepid warm water at 25 °C, in a random order) after administration of DW or drugs, daily for 21 days. Behavioural assessments were conducted on day 1 and day 21 (after which mice were sacrificed, blood taken for estimation of corticosterone levels and brain homogenates used for estimation of antioxidant activities). Administration of melatonin resulted in an increase in horizontal locomotion and self-grooming, while rearing showed a time-dependent increase, compared to non-stress and stress controls. Working memory improved with increasing doses of melatonin (compared to controls and diazepam); in comparison to setraline however, working memory decreased. A dose-related anxiolytic effect is seen when melatonin is compared to non-stressed and stressed controls. Melatonin administration reduced the systemic/oxidant response to repeated stress. Administration of melatonin in repeatedly stressed adolescent mice was associated with improved central excitation, enhancement of working memory, anxiolysis and reduced systemic response to stress.

Long-lasting monoaminergic and behavioral dysfunctions in a mice model of socio-environmental stress during adolescence

Adolescence is one of the critical periods of development and has great importance to health for an individual as an adult. Stressors or traumatic events during this period are associated with several psychiatric disorders as related to anxiety or depression and cognitive impairments, but whether negative experiences continue to hinder individuals as they age is not as well understood. We determined how stress during adolescence affects behavior and neurochemistry in adulthood. Using an unpredictable paradigm (2 stressors per day for 10days) in Balb/c mice, behavioral, hormonal, and neurochemical changes were identified 20days after the cessation of treatment. Adolescent stress increased motor activity, emotional arousal and vigilance, together with a reduction in anxiety, and also affected recognition memory. Furthermore, decreased serotonergic activity on hippocampus, hypothalamus and cortex, decreased noradrenergic activity on hippocampus and hypothalamus, and increased the turnover of dopamine in cortex. These data suggest behavioral phenotypes associated with emotional arousal, but not depression, emerge after cessation of stress and remain in adulthood. Social-environmental stress can induce marked and long-lasting changes in HPA resulting from monoaminergic neurotransmission, mainly 5-HT activity.

Effect of (4a) a novel 5-HT3 receptor antagonist on chronic unpredictable mild stress induced depressive-like behavior in mice: an approach using behavioral tests battery

BACKGROUND

The inconsistent therapeutic outcome necessitates designing and identifying novel therapeutic interventions for depression. Hence, the present study deals with the investigation of antidepressant-like effects of a novel 5-HT3 receptor antagonist (4-phenylpiperazin-1-yl) (quinoxalin-2-yl) methanone (4a) on chronic unpredictable mild stress (CUMS) induced behavioral and biochemical alterations.

METHODS

Animals were subjected to different stressors for a period of 28 days. On day 15 after the subsequent stress procedure, mice were administered with (4a) (2 and 4 mg/kg p.o.), escitalopram (10 mg/kg p.o.), or vehicle (10 mL/kg p.o.) until day 28 along with the CUMS. Thereafter, behavioral battery tests like locomotor score, sucrose preference test, forced swim test (FST), tail suspension test (TST), and elevated plus maze (EPM) were performed. Biochemical assays like lipid peroxidation, nitrite levels, reduced glutathione (GSH), catalase, and superoxide dismutase (SOD) were estimated in the mice brain homogenate.

RESULTS

(4a) Dose dependently attenuated the behavioral alterations by increasing the sucrose consumption, reducing the immobility time in FST and TST, increasing the open arm number of entries and time in EPM. Furthermore, biochemical alterations were reversed by (4a) as examined by reduced lipid peroxidation and nitrite levels and elevated antioxidant enzyme levels like GSH, catalase and SOD.

CONCLUSIONS

(4a) exhibits antidepressant potential by reversing the CUMS induced behavioral and biochemical changes in mice.

Overexpression of corticotropin-releasing factor receptor type 2 in the bed nucleus of stria terminalis improves posttraumatic stress disorder-like symptoms in a model of incubation of fear

BACKGROUND

Posttraumatic stress disorder (PTSD) is a severe, persistent psychiatric disorder in response to a traumatic event, causing intense anxiety and fear. These responses may increase over time upon conditioning with fear-associated cues, a phenomenon termed fear incubation. Corticotropin-releasing factor receptor type 1 (CRFR1) is involved in activation of the central stress response, while corticotropin-releasing factor receptor type 2 (CRFR2) has been suggested to mediate termination of this response. Corticotropin-releasing factor (CRF) receptors are found in stress-related regions, including the bed nucleus of stria terminalis (BNST), which is implicated in sustained fear.

METHODS

Fear-related behaviors were analyzed in rats exposed to predator-associated cues, a model of psychological trauma, over 10 weeks. Rats were classified as susceptible (PTSD-like) or resilient. Expression levels of CRF receptors were measured in the amygdala nuclei and BNST of the two groups. In addition, lentiviruses overexpressing CRFR2 were injected into the medial division, posterointermediate part of the BNST (BSTMPI) of susceptible and resilient rats and response to stress cues was measured.

RESULTS

We found that exposure to stress and stress-associated cues induced a progressive increase in fear response of susceptible rats. The behavioral manifestations of these rats were correlated both with sustained elevation in CRFR1 expression and long-term downregulation in CRFR2 expression in the BSTMPI. Intra-BSTMPI injection of CRFR2 overexpressing lentiviruses attenuated behavioral impairments of susceptible rats.

CONCLUSIONS

These results implicate the BNST CRF receptors in the mechanism of coping with stress. Our findings suggest increase of CRFR2 levels as a new approach for understanding stress-related atypical psychiatric syndromes such as PTSD.

Chronic administration of catechin decreases depression and anxiety-like behaviors in a rat model using chronic corticosterone injections

Previous studies have demonstrated that repeated administration of the exogenous stress hormone corticosterone (CORT) induces dysregulation in the hypothalamic-pituitary-adrenal (HPA) axis and results in depression and anxiety. The current study sought to verify the impact of catechin (CTN) administration on chronic CORT-induced behavioral alterations using the forced swimming test (FST) and the elevated plus maze (EPM) test. Additionally, the effects of CTN on central noradrenergic systems were examined by observing changes in neuronal tyrosine hydroxylase (TH) immunoreactivity in rat brains. Male rats received 10, 20, or 40 mg/kg CTN (i.p.) 1 h prior to a daily injection of CORT for 21 consecutive days. The activation of the HPA axis in response to the repeated CORT injections was confirmed by measuring serum levels of CORT and the expression of corticotrophin-releasing factor (CRF) in the hypothalamus. Daily CTN administration significantly decreased immobility in the FST, increased open-arm exploration in the EPM test, and significantly blocked increases of TH expression in the locus coeruleus (LC). It also significantly enhanced the total number of line crossing in the open-field test (OFT), while individual differences in locomotor activities between experimental groups were not observed in the OFT. Taken together, these findings indicate that the administration of CTN prior to high-dose exogenous CORT significantly improves helpless behaviors, possibly by modulating the central noradrenergic system in rats. Therefore, CTN may be a useful agent for the treatment or alleviation of the complex symptoms associated with depression and anxiety disorders.

Chronic administration of baicalein decreases depression-like behavior induced by repeated restraint stress in rats

Baicalein (BA), a plant-derived active flavonoid present in the root of Scutellaria baicalensis, has been widely used for the treatment of stress-related neuropsychiatric disorders including depression. Previous studies have demonstrated that repeated restraint stress disrupts the activity of the hypothalamic-pituitary-adrenal (HPA) axis, resulting in depression. The behavioral and neurochemical basis of the BA effect on depression remain unclear. The present study used the forced swimming test (FST) and changes in brain neurotransmitter levels to confirm the impact of BA on repeated restraint stress-induced behavioral and neurochemical changes in rats. Male rats received 10, 20, or 40 mg/kg BA (i.p.) 30 min prior to daily exposure to repeated restraint stress (2 h/day) for 14 days. Activation of the HPA axis in response to repeated restraint stress was confirmed by measuring serum corticosterone levels and the expression of corticotrophin-releasing factor in the hypothalamus. Daily BA administration significantly decreased the duration of immobility in the FST, increased sucrose consumption, and restored the stress-related decreases in dopamine concentrations in the hippocampus to near normal levels. BA significantly inhibited the stress-induced decrease in neuronal tyrosine hydroxylase immunoreactivity in the ventral tegmental area and the expression of brain-derived neurotrophic factor (BDNF) mRNA in the hippocampus. Taken together, these findings indicate that administration of BA prior to the repeated restraint stress significantly improves helpless behaviors and depressive symptoms, possibly by preventing the decrease in dopamine and BDNF expression. Thus, BA may be a useful agent for the treatment or alleviation of the complex symptoms associated with depression.

Long-term ω-3 fatty acid supplementation induces anti-stress effects and improves learning in rats

Chronic stress leads to secretion of the adrenal steroid hormone corticosterone, inducing hippocampal atrophy and dendritic hypertrophy in the rat amygdala. Both alterations have been correlated with memory impairment and increased anxiety. Supplementation with ω-3 fatty acids improves memory and learning in rats. The aim of this study was to evaluate the effects of ω-3 supplementation on learning and major biological and behavioral stress markers. Male Sprague-Dawley rats were randomly assigned to three experimental groups: 1) Control, 2) Vehicle, animals supplemented with water, and 3) ω-3, rats supplemented with ω-3 (100 mg of DHA+25 mg of EPA). Each experimental group was divided into two subgroups: one of which was not subjected to stress while the other was subjected to a restraint stress paradigm. Afterwards, learning was analyzed by avoidance conditioning. As well, plasma corticosterone levels and anxiety were evaluated as stress markers, respectively by ELISA and the plus-maze test. Restraint stress impaired learning and increased both corticosterone levels and the number of entries into the open-arm (elevated plus-maze). These alterations were prevented by ω-3 supplementation. Thus, our results demonstrate that ω-3 supplementation had two beneficial effects on the stressed rats, a strong anti-stress effect and improved learning.

Stress: Neurobiology, consequences and management

Stress, both physical and psychological, is attracting increasing attention among neuroresearchers. In the last 20 decades, there has been a surge of interest in the research of stress-induced manifestations and this approach has resulted in the development of more appropriate animal models for stress-associated pathologies and its therapeutic management. These stress models are an easy and convenient method for inducing both psychological and physical stress. To understand the behavioral changes underlying major depression, molecular and cellular studies are required. Dysregulation of the stress system may lead to disturbances in growth and development, and may this may further lead to the development of various other psychiatric disorders. This article reviews the different types of stress and their neurobiology, including the different neurotransmitters affected. There are various complications associated with stress and their management through various pharmacological and non-pharmacological techniques. The use of herbs in the treatment of stress-related problems is practiced in both Indian and Western societies, and it has a vast market in terms of anti-stress medications and treatments. Non-pharmacological techniques such as meditation and yoga are nowadays becoming very popular as a stress-relieving therapy because of their greater effectiveness and no associated side effects. Therefore, this review highlights the changes under stress and stressor and their impact on different animal models in understanding the mechanisms of stress along with their effective and safe management.

Cafeteria diet-induced obesity plus chronic stress alter serum leptin levels

Obesity is a disease that has become a serious public health issue worldwide, and chronic stressors, which are a problem for modern society, cause neuroendocrine changes with alterations in food intake. Obesity and chronic stress are associated with the development of cardiovascular diseases and metabolic disorders. In this study, a rat model was used to evaluate the effects of a hypercaloric diet plus chronic restraint stress on the serum leptin and lipids levels and on the weight of specific adipose tissue (mesenteric, MAT; subcutaneous, SAT and visceral, VAT). Wistar rats were divided into the following 4 groups: standard chow (C), hypercaloric diet (HD), stress plus standard chow (S), and stress plus hypercaloric diet (SHD). The animals in the stress groups were subjected to chronic stress (placed inside a 25 cm × 7 cm plastic tube for 1h per day, 5 days per week for 6 weeks). The following parameters were evaluated: the weight of the liver, adrenal glands and specific adipose tissue; the delta weight; the Lee index; and the serum levels of leptin, corticosterone, glucose, total cholesterol, and triglycerides. The hypercaloric diet induced obesity in rats, increasing the Lee index, weight, leptin, triglycerides, and cholesterol levels. The stress decreased weight gain even in animals fed a hypercaloric diet but did not prevent a significant increase in the Lee index. However, an interaction between the independent factors (hypercaloric diet and stress) was observed, which is demonstrated by the increased serum leptin levels in the animals exposed to both protocols.

Fucoidan prevents depression-like behavior in rats exposed to repeated restraint stress

Previous studies have demonstrated that repeated restraint stress in rodents increased depression-like behavior and altered the expression of corticotrophin-releasing factor in the hypothalamus. The current study focused on verifying the impact of fucoidan (FCN) administration on repeated restraint stress-induced behavioral responses using the forced swimming test (FST). Additionally, we examined the effect of FCN on the central noradrenergic system by observing changes in neuronal tyrosine hydroxylase (TH) immunoreactivity and brain-derived neurotrophic factor (BDNF) mRNA expression in the rat brains. Male rats received 10, 20, or 50 mg/kg FCN (i.p.) 30 min before daily exposures to repeated restraint stress (2 h/day) for 14 days. Repeated restraint stress increased immobility in the FST. Daily administration of FCN during the repeated restraint stress period significantly inhibited the stress-induced behavioral deficits in this behavioral test. Administration of FCN also significantly blocked the increase in TH expression in the locus coeruleus and the basolateral nucleus of the amygdala, and the decrease in BDNF mRNA expression in the hippocampus. Taken together, these findings indicate that administration of FCN prior to restraint stress significantly improved helpless behavior in rats, possibly through modulating the central noradrenergic system. Therefore, FCN may be a useful agent for treating complex symptoms of depression disorder.

Regulation of adult neurogenesis in the hippocampus by stress, acetylcholine and dopamine

Neurogenesis is well-established to occur during adulthood in two regions of the brain, the subventricular zone (SVZ) and the subgranular zone (SGZ) of the dentate gyrus in the hippocampus. Research for more than two decades has implicated a role for adult neurogenesis in several brain functions including learning and effects of antidepressants and antipsychotics. Clear understanding of the players involved in the regulation of adult neurogenesis is emerging. We review evidence for the role of stress, dopamine (DA) and acetylcholine (ACh) as regulators of neurogenesis in the SGZ. Largely, stress decreases neurogenesis, while the effects of ACh and DA depend on the type of receptors mediating their action. Increasingly, the new neurons formed in adulthood are potentially linked to crucial brain processes such as learning and memory. In brain disorders like Alzheimer and Parkinson disease, stress-induced cognitive dysfunction, depression and age-associated dementia, the necessity to restore brain functions is enormous. Activation of the resident stem cells in the adult brain to treat neuropsychiatric disorders has immense potential and understanding the mechanisms of regulation of adult neurogenesis by endogenous and exogenous factors holds the key to develop therapeutic strategies for the debilitating neurological and psychiatric disorders.

Cellular consequences of stress and depression

Stress is known to activate distinct neuronal circuits in the brain and induce multiple changes on the cellular level, including alterations in neuronal structures. On the basis of clinical observations that stress often precipitates a depressive disease, chronic psychosocial stress serves as an experimental model to evaluate the cellular and molecular alterations associated with the consequences of major depression. Antidepressants are presently believed to exert their primary biochemical effects by readjusting aberrant intrasynaptic concentrations of neurotransmitters, such as serotonin or noradrenaline, suggesting that imbalances viihin the monoaminergic systems contribute to the disorder (monoaminergic hypothesis of depression). Here, we reviev the results that comprise our understanding of stressful experience on cellular processes, with particular focus on the monoaminergic systems and structural changes within brain target areas of monoaminergic neurons.

Prefrontal-limbic change in dopamine turnover by acupuncture in maternally separated rat pups

The present study investigated the possible role of acupuncture in alleviating depression-like behavioral changes and examined changes in the levels of serotonin (5-HT), dopamine (DA), and their metabolites in the hippocampus (HP) and prefrontal cortex (PFC) of maternally separated rat pups. On postnatal day 15, rat pups were maternally separated and received acupuncture stimulation at acupoint HT7 or ST36 once a day for 7 days. Then, on postnatal day 21, a tail suspension test was performed, and the HP and PFC were harvested. Levels of 5-HT, 5-hydroxyindole-3-acetic acid (5-HIAA), DA, and 3,4-dihydroxyphenylacetic acid (DOPAC) in the tissue and corticosterone (CORT) in plasma were then measured. The total duration of immobility in maternally separated rat pups increased after maternal separation, and this increase was alleviated by acupuncture stimulation at HT7. The 5-HIAA/5-HT ratio and the levels of 5-HT and 5-HIAA were not significantly changed, but those of the DA and the DOPAC/DA ratio were significantly lower and that of CORT was significantly higher after maternal separation. The maternal separation-induced changes of the DOPAC/DA ratio and the CORT level significantly alleviated after acupuncture stimulation at HT7. These results suppose that the functional recovery of prefrontal-limbic system by acupuncture stimulation plays an important role in acupuncture-induced benefits in this animal model of depression.

Selective deletion of the leptin receptor in dopamine neurons produces anxiogenic-like behavior and increases dopaminergic activity in amygdala

The leptin receptor (Lepr) is expressed on midbrain dopamine neurons. However, the specific role of Lepr signaling in dopamine neurons remains to be clarified. In the present study, we generated a line of conditional knockout mice lacking functional Lepr selectively on dopamine neurons (Lepr(DAT-Cre)). These mice exhibit normal body weight and feeding. Behaviorally, Lepr(DAT-Cre) mice display an anxiogenic-like phenotype in the elevated plus-maze, light-dark box, social interaction and novelty-suppressed feeding tests. Depression-related behaviors, as assessed by chronic stress-induced anhedonia, forced swim and tail-suspension tests, were not affected by deletion of Lepr in dopamine neurons. In vivo electrophysiological recordings of dopamine neurons in the ventral tegmental area revealed an increase in burst firing in Lepr(DAT-Cre) mice. Moreover, blockade of D1-dependent dopamine transmission in the central amygdala by local microinjection of the D1 antagonist SCH23390 attenuated the anxiogenic phenotype of Lepr(DAT-Cre) mice. These findings suggest that Lepr signaling in midbrain dopamine neurons has a crucial role for the expression of anxiety and for the dopamine modulation of amygdala function.

Dopamine attenuates evoked inhibitory synaptic currents in central amygdala neurons

The central nucleus of the amygdala (CeA) plays a critical role in regulating the behavioral, autonomic and endocrine response to stress. Dopamine (DA) participates in mediating the stress response and DA release is enhanced in the CeA during stressful events. However, the electrophysiological effects of DA on CeA neurons have not yet been characterized. Therefore, the purpose of this study was to identify and characterize the effect of DA application on electrophysiological responses of CeA neurons in coronal brain sections of male Sprague-Dawley rats. We used whole-cell patch-clamp electrophysiological techniques to record evoked synaptic responses and to determine basic membrane properties of CeA neurons both before and after DA superfusion. DA (20-250 μM) did not significantly alter membrane conductance over the voltage range tested. However, DA significantly reduced the peak amplitude of evoked inhibitory synaptic currents in CeA neurons. Pretreatment with the D(2) receptor antagonist eticlopride failed to significantly block the inhibitory effects of DA. In contrast, pretreatment with the D(1) receptor antagonist SCH-23390 significantly reduced the effects of DA on evoked inhibitory neurotransmission in these neurons. Moreover, bath superfusion of the specific D(1) receptor agonist SKF-39393, but not the D(2) receptor agonist quinpirole, significantly reduced peak amplitude of evoked inhibitory synaptic events. DA reduced the frequency of miniature IPSCs without altering the amplitude, while having no effect on the amplitude of IPSCs elicited by pressure application of GABA. These results suggest that DA may modulate inhibitory synaptic transmission in CeA through D(1) receptor activation primarily by a presynaptic mechanism.

Alterations in monoamine levels and oxidative systems in frontal cortex, striatum, and hippocampus of the rat brain during chronic unpredictable stress

Stress plays a key role in the induction of various clinical disorders by altering monoaminergic response and antioxidant defenses. In the present study, alterations in the concentrations of dopamine (DA), serotonin (5-HT) and their metabolites, and simultaneous changes in the antioxidant defense system and lipid peroxidation in different brain regions (frontal cortex, striatum, and hippocampus) were investigated immediately and 24 h after exposure to chronic unpredictable stress (CUS). CUS involved subjecting Sprague-Dawley rats to two different types of stressors varying from mild to severe intensity every day in an unpredictable manner, over a period of 7 days. CUS significantly decreased DA and 5-HT concentrations, with increased DA turnover ratios in the selected brain regions. In the frontal cortex and striatum, DA metabolite concentrations were increased; however, in the hippocampus they remained unaltered. Further, a decrease of 5-hydroxyindoleacetic acid content was observed in the frontal cortex and striatum, with no significant alteration in the hippocampus. CUS also reduced the activities of superoxide dismutase and catalase, with increased lipid peroxidation and decreased glutathione levels in the selected brain regions. Glutathione peroxidase activity was increased in the frontal cortex and hippocampus only. The pattern of CUS-induced monoamine and oxidative changes immediately after the last stressor and 24 h later were similar when compared with the control group, indicating that the observed changes were due to the chronic exposure to the various stressors and were not merely acute effects of the last stressor. The altered redox state in the striatum and frontal cortex might be related to the perturbed DA and/or 5HT levels, while the hippocampus seems to be less influenced by CUS in terms of monoamine metabolite changes. These results suggest that the perturbed monoamine levels could interact with the oxidative load during CUS. Hence, the current study has implications for pharmacological interventions targeting both central monoamines and cellular antioxidants as a potential stress management strategy for protecting against central stress-induced disorders.

MDMA pretreatment leads to mild chronic unpredictable stress-induced impairments in spatial learning

3,4-Methylenedioxymethamphetamine (MDMA) is a drug of abuse worldwide and a selective serotonin (5-HT) neurotoxin. An important factor in the risk of drug abuse and relapse is stress. Although multiple parallels exist between MDMA abuse and stress, including effects on 5-HTergic neurotransmission, few studies have investigated the consequences of combined exposure to MDMA and chronic stress. Therefore, rats were pretreated with MDMA and exposed 7 days later to 10 days of mild chronic unpredictable stress (CUS). MDMA pretreatment was hypothesized to enhance the effects of CUS leading to enhanced 5-HT transporter (SERT) depletion in the hippocampus and increased anxiety and cognitive impairment. Whereas MDMA alone increased anxiety-like behavior on the elevated plus maze, CUS alone or in combination with MDMA pretreatment did not increase anxiety-like behavior. In contrast, MDMA pretreatment led to CUS-induced learning impairment in the Morris water maze but not an enhanced depletion of hippocampal SERT protein. These results show that prior exposure to MDMA leads to stress-induced impairments in learning behavior that is not otherwise observed with stress alone and appear unrelated to an enhanced depletion of SERT.

Evidence for sex-specific shifting of neural processes underlying learning and memory following stress

Recent human research has been focused upon determining whether there is evidence that stress responses cause qualitative changes in neural activity such that people change their learning strategies from a spatial/contextual memory process through the hippocampus to a procedural stimulus-response process through the caudate nucleus. Moreover, interest has shifted to determining whether males and females exhibit the same type of stress-induced change in neural processing of associations. Presented is a select review of 2 different animal models that have examined how acute or chronic stressors change learning in a sex-specific manner. This is followed by a brief review of recent human studies documenting how learning and memory functions change following stressor exposure. In both cases, it is clear that ovarian hormones have a significant influence on how stress affects learning processes in females. We then examine the evidence for a role of acetylcholine, dopamine, norepinephrine, or serotonin in modulating this shifting of processing and how that may differ across sex. Conclusions drawn suggest that there may be evidence for sex-specific changes in amygdala and hippocampus neuromodulation; however, the behavioral data are still not conclusive as to whether this represents a common or sex-specific shift in how males and females process associations after stressor exposure.

Modulation of extracellular monoamine transmitter concentrations in the hippocampus after weak and strong tetanization of the perforant path in freely moving rats

Hippocampal long-term potentiation (LTP) is considered as a cellular model of memory formation. Specific, electrical weak tetanization of distinct afferents such as the medial perforant path results in a short-lasting, protein synthesis-independent early-LTP (up to 4 h) within the dentate gyrus. A stronger tetanization leads to late-LTP (>4 h), which is protein synthesis-dependent and requires heterosynaptic activation during its induction, the latter of which can be provided by afferents from cortical brain regions or subcortical nuclei during memory formation in the behaving animal. In particular, noradrenaline (NA) is required for late-LTP in the dentate gyrus and dopamine for late-LTP in the apical CA1-dendrites. However, little is known about the concentrations and temporal dynamics of such neuromodulators like NA, serotonin (5-HT) and dopamine (DA) during LTP. We now implemented the microdialysis method to study this topic after stimulating the dentate gyrus in more detail. A weak tetanus of the perforant path, which normally leads to early-LTP, transiently but significantly decreased the concentration of NA (3 h) and increased the concentration of 5-HT (about 2 h) and DA (about 1 h) in the hippocampus. A strong tetanus, normally resulting in late-LTP, increased concentrations of NA and DA significantly and long-lasting (for about 5 h), whereas 5-HT concentration was increased with a delay (after about 30 min) and only for a short time (30 min). Thus different stimulation protocols resulted in different release patterns of neuromodulators, that may support discriminative processing of incoming information in the hippocampus.

WFS1 gene as a putative biomarker for development of post-traumatic syndrome in an animal model

Post-traumatic stress disorder (PTSD) is an anxiety disorder that may develop after the experiencing or witnessing of a life-threatening event. PTSD is defined by the coexistence of three clusters of symptoms: re-experiencing, avoidance and hyperarousal, which persist for at least 1 month in survivors of the event (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition). Using an established model of PTSD, we addressed the well-accepted clinical finding that only a minority (about 20%) of the individuals exposed to a traumatic event develop PTSD. Moreover, we followed individual rat behavior for up to a month, and then treated the PTSD-like animals with citalopram. Our data demonstrate high face (20% of rats exposed to a reminder of the stressor develop symptoms characteristic of PTSD) and predictive (response to citalopram) validities. Based on these validities we identified alterations in the Wolframin gene in the CA1 and amygdala regions, specifically in exposed PTSD-like rats, which were normalized after treatment with citalopram. We suggest the Wolframin gene as a putative biomarker for PTSD. Since Wolframin gene undergoes alternative splicing and has polymorphism in the population, it may serve a future marker for identification of the vulnerable population exposed to a traumatic event.