Chronic Restraint Stress Group Research Articles

Neuroprotective Role of Selenium Nanoparticles Against Behavioral, Neurobiochemical and Histological Alterations in Rats Subjected to Chronic Restraint Stress.

Chronic stress induces changes in the prefrontal cortex and hippocampus. Selenium nanoparticles (SeNPs) showed promising results in several neurological animal models. The implementation of SeNPs in chronic restraint stress (CRS) remains to be elucidated. This study was done to determine the possible protective effects of selenium nanoparticles on behavioral changes and brain oxidative stress markers in a rat model of CRS. 50 rats were divided into three groups; control group (n = 10), untreated CRS group (n = 10) and CRS-SeNPs treated group (n = 30). Restraint stress was performed 6 h./day for 21 days. Rats of CRS-SeNPs treated group received 1, 2.5 or 5 mg/kg SeNPs (10 rats each) by oral gavage for 21 days. Rats were subjected to behavioral assessments and then sacrificed for biochemical and histological analysis of the prefrontal cortex and hippocampus. Prefrontal cortical and hippocampal serotonin levels, oxidative stress markers including malondialdehyde (MDA), reduced glutathione (GSH) and glutathione peroxidase (GPx), tumor necrosis factor alpha (TNF-α) and caspase-3 were assessed. Accordingly, different doses of SeNPs showed variable effectiveness in ameliorating disease parameters, with 2.5 mg/kg dose of SeNPs showing the best improving results in all studied parameters. The present study exhibited the neuroprotective role of SeNPs in rats subjected to CRS and proposed their antioxidant, anti-inflammatory and anti-apoptotic effects as the possible mechanism for increased prefrontal cortical and hippocampal serotonin level, ameliorated anxiety-like and depressive-like behaviors and improved prefrontal cortical and hippocampal histological architecture.

Chronic restraint stress induces abnormal behaviors in pain sensitivity and cognitive function in mice: the role of Keap1/Nrf2 pathway

Stress is a series of physical and psychological responses to external and internal environmental stimuli. Growing studies have demonstrated the detrimental impacts of acute restraint stress (ARS) and chronic restraint stress (CRS) on animal behavior. However, the related pathogenesis and therapeutic mechanisms remain unclear. Hence, the present study aimed to examine whether unfolded protein response (UPR) and Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2 related factor 2 (Nrf2) pathway are associated with ARS- and CRS- induced abnormal behaviors of pain sensitivity and cognitive function. We here used four behavioral tests to evaluate pain sensitivity and cognitive function in ARS and CRS mice. CRS markedly decreased Paw Withdrawal Mechanical Threshold (PWMT) and Tail-flick Latency (TFL) scores, whereas ARS altered TFL but had no effect on PWMT scores. Additionally, CRS, but not ARS, significantly changed behaviors in nest building behavior and MWMT. Intriguingly, the expression of Keap1 and Nrf2 protein were decreased in the spinal cord and hippocampus in CRS mice, but not in ARS mice. Moreover, neither the ARS nor the CRS groups significantly differed from the control group in terms of endoplasmic reticulum stress (ERS). Taken together, this study demonstrated that CRS could induce abnormal pain sensitivity and cognitive function probably via Keap1/Nrf2 pathway in spinal cord and hippocampus. It is therefore likely that effective intervention of Keap1/Nrf2 pathway may contribute to preventing and treating hyperalgesia and cognitive dysfunction in CRS.

Comparative effects of the alcoholic extract of Terminalia chebula and crocin on stress‑induced anxiety‑like behavior and memory impairment in male rats.

Crocin and Terminalia chebula (T. chebula) were proven to have neuroprotective effects. In this study, we evaluated the preventive effects of crocin and alcoholic extract of the T. chebula alone and in combination to examine their efficacy against chronic restraint stress (CRS)‑induced cognitive impairment, anxiety‑like behaviors, hippocampal synaptic plasticity deficit as well as neuronal arborization damage in the hippocampal CA1 neurons. Over 14 consecutive days, animals received crocin, T. chebula, or their combination (5 min before CRS). The elevated plus‑maze results showed that crocin and T. chebula alone and in combination treatment significantly increased the time spent in open arms, percentage of open arm entries, and head dipping as compared with the CRS group. Barnes maze results showed that administration of crocin and T. chebula alone and their combination significantly improves spatial memory indicators such as distance traveled, latency time to achieving the target hole, and the number of errors when compared to the CRS group. These learning deficits in CRS animals correlated with a reduction of long-term potentiation (LTP) in hippocampal CA1 synapses, which both T. chebula and crocin treatment improved field excitatory postsynaptic potentials (fEPSP) amplitude and fEPSP slope reduction induced by CRS. Golgi‑Cox staining showed that T. chebula and crocin treatment increased the number of dendrites and soma arbors in the CA1 neurons compared with the CRS group. Our results suggest that both T. chebula and crocin attenuated CRS‑induced anxiety‑like behaviors, memory impairment, and synaptic plasticity loss in hippocampal CA1 neurons. We found no significant difference between single treatments of T. chebula or crocin and their combination in protecting CRS‑induced anxiety‑like behaviors, memory impairment, and synaptic plasticity loss in hippocampal CA1 neurons.

Functional magnetic resonance imaging study on anxiety and depression disorders induced by chronic restraint stress in rats

Persistent and negative stress stimulation is one of the most important factors leading to anxiety and depression in individuals, and it can negatively affect the normal function and structure of brain-related regions. However, the maladaptive changes of brain neural networks in anxiety and depression induced by chronic stress have not been explored in detail. In this study, we analyzed the changes in global information transfer efficiency, stress related blood oxygen level dependent (BOLD)- and diffusion tensor imaging (DTI)- signals and functional connectivity (FC) in rat models based on resting-state functional magnetic resonance imaging (rs-fMRI). The results showed that compared to control group, rats treated with chronic restraint stress (CRS) for 5 weeks had reconstructed the small-world network properties. In addition, CRS group had increased coherence and activity in bilateral Striatum (ST_R & L), but decreased coherence and activity in unilateral (left) Frontal Association Cortex (FrA_L) and unilateral (left) Medial Entorhinal Cortex (MEC_L). DTI analysis and correlation analysis confirmed the disrupted integrity of MEC_L and ST_R & L and their correlation to anxiety- and depressive-liked behaviors. Functional connectivity further showed these regions of interest (ROI) had decreased positive correlations with several brain areas, respectively. Our study comprehensively revealed the adaptive changes of brain neural networks induced by chronic stress and emphasized the abnormal activity and functional connectivity of ST_R & L and MEC_L in the pathological condition.

Induced Inflammatory and Oxidative Markers in Cerebral Microvasculature by Mentally Depressive Stress.

Cerebrovascular disease (CVD) is recognized as the leading cause of permanent disability worldwide. Depressive disorders are associated with increased incidence of CVD. The goal of this study was to establish a chronic restraint stress (CRS) model for mice and examine the effect of stress on cerebrovascular inflammation and oxidative stress responses. A total of forty 6-week-old male C57BL/6J mice were randomly divided into the CRS and control groups. In the CRS group (n = 20), mice were placed in a well-ventilated Plexiglas tube for 6 hours per day for 28 consecutive days. On day 29, open field tests (OFT) and sucrose preference tests (SPT) were performed to assess depressive-like behaviors for the two groups (n = 10/group). Macrophage infiltration into the brain tissue upon stress was analyzed by measuring expression of macrophage marker (CD68) with immunofluorescence in both the CRS and control groups (n = 10/group). Cerebral microvasculature was isolated from the CRS and controls (n = 10/group). mRNA and protein expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), vascular cell adhesion molecule-1 (VCAM-1), and macrophage chemoattractant protein-1 (MCP-1) in the brain vessels were measured by real-time PCR and Western blot (n = 10/group). Reactive oxygen species (ROS), hydrogen peroxide (H2O2), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activities were quantified by ELISA to study the oxidative profile of the brain vessels (n = 10/group). Additionally, mRNA and protein expressions of NOX subunits (gp91phox, p47phox, p67phox, and p22phox) in the cerebrovascular endothelium were analyzed by real-time PCR and Western blot (n = 10/group). CRS decreased the total distances (p < 0.05) and the time spent in the center zone in OFT (p < 0.001) and sucrose preference test ratio in SPT (p < 0.01). Positive ratio of CD68+ was increased with CRS in the entire region of the brain (p < 0.001), reflecting increased macrophage infiltration. CRS increased the expression of inflammatory factors and oxidative stress in the cerebral microvasculature, including TNF-α (p < 0.001), IL-1β (p < 0.05), IL-6 (p < 0.05), VCAM-1 (p < 0.01), MCP-1 (p < 0.01), ROS (p < 0.001), and H2O2 (p < 0.001). NADPH oxidase (NOX) was activated by CRS (p < 0.01), and mRNA and protein expressions of NOX subunits (gp91phox, p47phox, p67phox, and p22phox) in brain microvasculature were found to be increased. To our knowledge, this is the first study to demonstrate that CRS induces depressive stress and causes inflammatory and oxidative stress responses in the brain microvasculature.

ROLE OF SELENIUM SUPPLEMENTATION ON ANTIOXIDANT CHANGES IN WISTAR ALBINO RATS AFTER CHRONIC RESTRAINT STRESS

Objective: Stress is a non-specific response of the body to any physical or physiological demand. Oxidative stress may occur due to imbalance between pro-oxidants and antioxidants. Restraint stress or immobilization has been used extensively as a stressor for the study of stress-related biological, biochemical, and physiological responses in animals. Nutritional treatment by exogenous supplementation of antioxidants like selenium reactivates which guard against the insult caused ROS during the repeated restraint stress. The objective of the study is to determine the role of selenium on antioxidant changes in Wistar albino rats after chronic restraint stress. Methods: Adult male Wistar albino rats weighing about 180–200 g were taken for the study and were divided into three groups – the control group (n=6) chronic restraint stress group (n=6) and chronic stress treated with selenium (n=6). Restraint stress was given in wire mesh restrainers for 30 days (6 h/day), and the blood from the jugular vein was collected for estimation of antioxidant status (Superoxide dismutase, Glutathione peroxidase, CAT, Vit C, and Vit E) in rats. Results: One-way analysis of variance statistical test was used to analyses the mean and SD among the groups. The rats pre-treated with selenium (p&lt;0.001) showed a significant decrease in lipid peroxidation. In chronic restraint stress, albino rats administered with Selenium showed a significant increase (p&lt;0.001) in enzymatic and non-enzymatic antioxidant activity when compared to controls. Conclusion: The effect of the Selenium acts as a antidote to counteract the effects of restraint stress and has significant therapeutic application in counter acting oxidative damage on Wistar albino rats.

High-cholesterol diet promotes depression- and anxiety-like behaviors in mice by impact gut microbe and neuroinflammation

Neuropsychiatric disorders, including anxiety and depression, are one of the most common mental illnesses worldwide. A growing body of evidence shows that there is a complex relationship between dietary patterns and mental health. In our study, C57BL/6J mice were divided into three groups: control diet group (CON, 10 % kcal fat), high-cholesterol diet model group (HCD, 42.0 % kcal fat + 1.25 % kcal Cholesterol), and chronic restraint stress group (CRS, 10 % kcal fat) which as a positive control group for the depression model. Six weeks later, depressive- and anxiety-like behavior were evaluated for using the OFT, SPT and TST. Glucose intolerance and liver fat were detected by IGTT and liver lipid kit. The expression of peripheral and central inflammation was detected by LEGEND plex kits. 5-HT (also named 5-hydroxytryptamine, 5-HT) and related receptors expression were monitored by ELISA, RT-PCR and Western blot. Meantime, gut microbe of stool samples was performed by 16S rRNA gene sequencing. Similar to CRS model, short-term HCD intervention induced anxiety and depression-like behavior behavioral abnormalities in mice. HCD consumption resulted in significantly increased body weight, liver fat (LDL-C, TC, TG), peripheral inflammation (IL-1β, MCP-1, IL-17A) and neuroinflammation (MCP-1). The concentration of 5-HT increased in the hippocampus, meanwhile, the expression of 5-HT receptor HTR2A was distinct in different regions of the brain tissue. More importantly, we found that compared with the CON diet, HCD induced the decrease of intestinal flora diversity, especially the decrease the relative abundance of Akkermansia_muciniphila, which was statistically significant. Further, Pearson correlation analysis showed that Akkermansia_muciniphila was significantly negatively correlated with the concentration of MCP-1, IL-17A in serum and 5-HT in hippocampus. Therefore, we speculated that the disorder of neuroinflammation induced by HCD consumption promotes depression- and anxiety-like behaviors in mice through the gut microbe.

γ-Aminobutyric acid promotes the inhibition of hair growth induced by chronic restraint stress

Stress plays a critical role in hair loss, although the underlying mechanisms are largely unknown. γ-aminobutyric acid (GABA) has been reported to be associated with stress; however, whether it affects stress-induced hair growth inhibition is unclear. This study aimed to investigate the potential roles and mechanisms of action of GABA in chronic restraint stress (CRS)-induced hair growth inhibition. We performed RNA-seq analysis and found that differentially expressed genes (DEGs) associated with neuroactive ligand-receptor interaction, including genes related to GABA receptors, significantly changed after mice were treated with CRS. Targeted metabolomics analysis and enzyme-linked immunosorbent assay (ELISA) also showed that GABA levels in back skin tissues and serum significantly elevated in the CRS group. Notably, CRS-induced hair growth inhibition got aggravated by GABA and alleviated through GABAA antagonists, such as picrotoxin and ginkgolide A. RNA sequencing analysis revealed that DEGs related to the cell cycle, DNA replication, purine metabolism, and pyrimidine metabolism pathways were significantly downregulated in dermal papilla (DP) cells after GABA treatment. Moreover, ginkgolide A, a GABAA antagonist extracted from the leaves of Ginkgo biloba, promoted the cell cycle of DP cells. Therefore, the present study demonstrated that the increase in GABA could promote CRS-induced hair growth inhibition by downregulating the cell cycle of DP cells and suggested that ginkgolide A may be a promising therapeutic drug for hair loss.

Viral metagenomics combined with metabolomics reveals the role of gut viruses in mouse model of depression

Depression is a heterogeneous mental disorder that has been linked to disturbances in the gut microbiome. As an essential part of the gut microbiome, gut virome may play critical roles in disease progression and development. However, the relationship between the effect of gut virome on neurotransmitter metabolism and depression is unknown. We evaluated the alterations of gut virome and neurotransmitters in chronic restraint stress (CRS)-induced mouse model of depression based on viral metagenomics and LC-MS/MS metabolomics analyses. The results reveal that the gut virome profile of CRS group differed significantly from CON group. Microviridae was the most abundant differential viral family in both groups, followed by Podoviridae, while Siphoviridae was only enriched in CRS group of the top 100 differential viruses. The differential viruses that predicted to Enterobacteriaceae phage, Gammaproteobacteria phage and Campylobacteraceae phage were enriched in CRS group. Furthermore, 12 differential neurotransmitters primarily involved in the tryptophan metabolism pathway were altered in depressive-like mice. Besides, tryptamine and 5-methoxytryptamine hydrochloride were strongly associated with differential viruses belonging to Podoviridae and Microviridae. Our findings provide new insight into understanding the potential role of the gut virome and metabolites in depression.

KXS Balances the Tryptophan Metabolism in Mild to Moderate Depressed Patients and Chronic Restraint Stress Induced Depressive Rats.

Tryptophan metabolism is involved in the etiology and exacerbation of depressive disorders. Kai-Xin-San (KXS), a traditional Chinese medicine formula, has been widely used to treat depression and modulate serotonin simultaneously, but how it regulates depressive-like behavior by shifting the balance of the tryptophan-serotonin metabolism and kynurenine pathway remains vague. Ten participants with mild to moderate depression treated with KXS (KXS preparation) were analyzed in this study. Depression rating scale score and the concentration of serum tryptophan, 5-hydroxytryptophan and kynurenine was measured at baseline and the endpoint of KXS treatment. To explore the specific regulatory mechanism of KXS in tryptophan metabolism, the chronic restraint stress (CRS) was used to induce depressive-like syndrome in rats and the hippocampus level of tryptophan, 5-hydroxytryptophan, kynurenine with downstream metabolites (kynurenic acid, quinolinic acid) and key enzymes (indoleamine 2,3-dioxygenase, kynurenine 3-monooxygenase, kynurenine aminotransferase) were analyzed by liquid chromatography-electros pray ionization tandem mass spectrometry, high performance liquid chromatography and enzyme-linked immunosorbent assay respectively. KXS significantly decreased depression rating scale scores and increased the serum tryptophan and kynurenine concentration in depressive patients compared to baseline. Also, it alleviated the depressive behavior in CRS rats obviously. Comparing with CRS group, KXS increased tryptophan, 5-hydroxytryptophan, kynurenine level in rat hippocampus. Furthermore, in kynurenine pathway, KXS decreased the expression of indoleamine 2,3-dioxygenase, increased kynurenic acid by upregulating the expression of kynurenine aminotransferase while decreased quinolinic acid level in hippocampus, which suggested that KXS more favored improving serotonin pathway, and neuroprotective kynurenic acid branch in the tryptophan metabolism. This is the first tryptophan metabolomic study of patients with depression undergoing KXS treatment. Combining these clinical results with CRS induced rat model studies, it verified that KXS achieves an excellent antidepressant effect and balances tryptophan-kynurenine metabolic pathways by regulating some key metabolic products and enzymes.

Lycopene Alleviates Chronic Stress-Induced Liver Injury by Inhibiting Oxidative Stress-Mediated Endoplasmic Reticulum Stress Pathway Apoptosis in Rats.

The liver is the major organ of metabolism and is extremely vulnerable to chronic stress. Lycopene (LYC) is a natural carotenoid with potent antioxidant and chronic disease potential. However, whether LYC protects against chronic restraint stress (CRS)-induced liver injury and the underlying mechanisms remain unclear. In this study, rats were restrained for 21 days for 6 h per day, with or without gavage of LYC (10 mg/kg). Serum ALT (85.99 ± 4.07 U/L) and AST (181.78 ± 7.35 U/L) and scores of liver injury were significantly increased in the CRS group. LYC significantly promoted the nuclear translocation of Nrf2, elevated the expression of antioxidant genes, and attenuated reactive oxygen radicals (ROS) levels within the liver. Cellular thermal shift assay (CETSA) and molecular docking results indicated that LYC competitively binds to Keap1 with the lowest molecule affinity of -9.0 kcal/mol. Moreover, LYC significantly relieved the hepatic endoplasmic reticulum swelling and decreased the expression of endoplasmic reticulum stress (ERS) hallmarks like GRP78, CHOP, and cleaved caspase-12. Meanwhile, LYC also mitigated CRS-induced hepatocyte apoptosis. Interestingly, every other day, the intraperitoneal injection of the Nrf2 inhibitor brusatol (0.4 mg/kg) significantly counteracted the protective effect of LYC. In conclusion, LYC protects against CRS-induced liver injury by activating the Nrf2 signaling pathway, scavenging ROS, and further attenuating ERS-associated apoptosis pathways.

Effects of SIRT1 in amygdala on chronic restraint stress-induced depression-like behaviors in rats

To investigate the effects of silent information regulator 1 (SIRT1) in amygdala on depression-like behaviors in rats using chronic restraint stress (CRS) as a model of depression. Sixty male SD rats were randomly divided into six groups (n=10 per group): control group (Control), chronic restraint stress group (CRS), CRS + fluoxetine-treated group (CRS + FLU), CRS + saline-treated group (CRS + NaCl), CRS + SIRT1-overexpression group (CRS + AAV-SIRT1), and CRS + empty vector group (CRS + AAV-EGFP). Except for the control group, rats from the other groups were exposed to chronic restraint stress for 21 days. After the modeling, rats in fluoxetine-treated group and saline-treated group were, respectively, treated with fluoxetine (10 mg/kg) or saline (10 mg/kg) by gavage every day for 3 weeks; AAV-SIRT1 or AAV-EGFP was, respectively, stereotaxically injected into the amygdala of rats in SIRT1-overexpression group and empty vector group, and the virus was expressed for 3 weeks. Rats in normal control group and CRS model group were not given any drug treatment. The depression-like behaviors of rats in each group were evaluated by sugar preference test (SPT), open field test (OFT) and forced swimming test (FST). SIRT1 expression in amygdala of rats was assessed by using immunoblot blotting. The number of SIRT1-positive cells in amygdala of rats was detected by immunofluorescence technique. Compared with the normal control group, the level of SIRT1 protein and the number of SIRT1+ cells in amygdala of the CRS-exposed rats were decreased significantly (P＜0.01), and CRS-exposed rats showed a significant decrease in sucrose preference (P＜0.01), less total horizontal distance (P＜0.01) and less time entered the center field (P＜0.01) in the OFT, a significant increase in the immobility time of the FST (P＜0.01). Fluoxetine treatment (P＜0.05, P＜0.01) or SIRT1 overexpression (P＜0.01) partially reversed the down-regulation of SIRT1 protein and SIRT1+ cells in amygdala of CRS-exposed rats and significantly improved the depression-like behaviors of CRS rats. Fluoxetine treatment partially reversed the down-regulation of SIRT1 level and the number of SIRT1+ in CRS rats, and significantly improved the depression-like behaviors. The antidepressant effect of fluoxetine treatment may be related to the up-regulation of SIRT1 in the amygdala of CRS-exposed rats.

Zanthoxylum Alatum Attenuates Chronic Restraint Stress Adverse Behavioral Effects Via the Mitigation of Oxidative Stress and Modulating the Expression of Genes Involved in Endoplasmic Reticulum Stress in Mice.

The functions of the endoplasmic reticulum (ER) are important, particularly in the proteins' synthesis, folding, modification, and transport. Based on traditional medicine and our previous studies on Zanthoxylum alatum in lipopolysaccharide-induced depressive behavior and scopolamine-induced impaired memory, the present study explored the role of hydroalcoholic extract of Z. alatum (ZAHA) seeds in reducing the ER stress in mice. The mice were restrained for 28 days in polystyrene tubes. ZAHA (100 and 200 mg/kg, PO) and imipramine (10 mg/kg, IP) were administered daily, 45 min before restraint from day 22 to 28. The mice were assessed by the forced swim test. Also, the antioxidant enzyme levels of Superoxide Dismutase (SOD), reduced glutathione (GSH), and lipid peroxidation (LPO) were measured in the hippocampus of mice. The expression of 78 kDa glucose-regulated protein (GRP78), 94 kDa Glucose-Regulated Protein (GRP94), and C/EBPhomologous protein (CHOP) genes was assessed by real-time PCR to explore the molecular mechanism. ZAHA (100 and 200 mg/kg, PO, and imipramine, IP) counteracted the stress by significantly reducing the immobility time in the force swimming test, receding oxidative stress and lipid peroxidation. The antioxidant enzyme (SOD and GSH) levels were elevated in the restraint stress group. Down-regulation of genes (GRP78, GRP94, and CHOP) compared to the chronic restraint stress group indicated stress modulating properties of the seeds in ER stress. Hesperidin, magnoflorine, melicopine, and sesamin, isolated from the active extract, were hypothesized to exert the activity. It can be concluded that Z. alatum reverted chronic restraint stress through its antioxidant properties and down-regulation of genes involved in ER stress.

Effects of Chronic Restraint Stress on Apoptosis of Amygdala Cells in Rats.

To explore the damage effects of chronic restraint stress (CRS) on amygdala cells through the rat CRS model. The rat CRS model was established, and the changes in body weight and adrenal mass in control group and CRS group were monitored at 1 d, 7 d, 14 d and 21 d. The behavior changes were evaluated by the percentage of retention time of open arms and open arm entries using the elevated plus maze (EPM). ELISA was used to detect the concentrations of rat's corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and cortisol. The changes of expression of glucocorticoid receptor (GR) and glial fibrillary acidic protein (GFAP) in amygdala were determined by immunohistochemistry and Western blotting. Ultrastructure changes of glial cell were observed by transmission electron microscopy. The apoptosis rate of amygdala was measured by flow cytometry. Compared with the control group at the same time points, body weight of CRS 1 d, 7 d, 14 d and 21 d groups increased slowly, but adrenal mass increased significantly; the serum level of CRH, cortisol and ACTH increased significantly at 7 d, 14 d and 21 d respectively; the expression of GR in amygdala was increased while that of GFAP was decreased; EPM test suggested that the percentage of retention time of open arms and open arm entries decreased significantly after 14 d. The CRS group showed different degrees of glial cell damage in amygdala, and the apoptosis rate of glial cell was significantly increased in 21 d group. This study successfully established a CRS model in rats, and anxiety-like behavioral changes in model rats may be caused by apoptosis of amygdala astrocytes.

Chronic restraint stress induces gastrointestinal function alternation: A potential role of the ArhGEF18-RhoA/Rho signaling pathway in the brain–gut axis under stress

Depression is one of the common psychiatric diseases worldwide. Previous studies showed that chronic stress could increase defecation and inhibit weight gain; however, the effects of chronic stress on gastrointestinal peristalsis had not been clarified. To study the mechanisms of depression, chronic restraint stress (CRS) is widely used as a traditional depressive animal model. In this study, we investigate the effects of CRS on gastric emptying and intestinal propulsion in mice. Our results showed that the mice exhibited obvious depression-like behaviors 4 weeks after CRS. Compared with the control group, gastric emptying and intestinal propulsion were significantly decreased in the CRS group. Further, we examined the expression of ArhGEF18, a Rho-specific guanine nucleotide exchanging factor, which was significantly reduced in the gut in the CRS group. Therefore, CRS caused depressive behaviors and abnormal gastrointestinal function. The ArhGEF18-RhoA/Rho signaling pathway may be a potential mediator in the brain–gut axis under stress.

Hypothalamic Kisspeptin Neurons Regulates Energy Metabolism and Reproduction Under Chronic Stress.

BackgroundStress activates the hypothalamic-pituitary-adrenal (HPA) axis, affecting energy homeostasis and reproduction. The aim of this study was to investigate whether stress affected energy metabolism and reproduction through the glucocorticoid receptor on Kisspeptin neurons in the hypothalamus.MethodsFour groups included control group, chronic restraint stress group, Kisspeptin specific glucocorticoid receptor knock out group (KGRKO) and KGRKO+stress group. Body weight, food intake, estrous cycle of female mice, serum sex hormone levels, serum corticosterone and prolactin, Kisspeptin expression in the hypothalamus were measured.ResultsThe restraint stress group showed a significant weight loss compared with the control group. KGRKO+restraint stress group had a reduced weight loss, suggesting that restraint stress might partially affect the energy metabolism through GR on Kisspeptin neurons. In terms of reproductive function, the restraint stress group and the KGRKO+restraint stress group showed missing pre-estrus period or prolonged estrous cycles. Serum LH and FSH in KGRKO + restraint stress group decreased significantly compared with KGRKO group. However, no significant difference in the level of serum testosterone was observed. After restraint stress, the levels of serum cortisol and prolactin in male and female mice were significantly higher than the control group, and the hypothalamus Kiss1 gene mRNA expression and Kisspeptin protein expression were significantly decreased.ConclusionChronic restraint stress induced weight loss and negative changes in reproduction, which were partially mediated by glucocorticoid receptor on Kisspeptin neurons in the hypothalamus.

Gut microbiota and its role in stress-induced hyperalgesia: Gender-specific responses linked to different changes in serum metabolites

Long-term stress causes hyperalgesia; and there are gender differences in the mechanism of pain in male and female individuals. The role of gut microbiota in pain has also been verified. However, whether gut microbiota plays a role in hyperalgesia caused by chronic restraint stress (CRS) with gender differences has not been explored. This study investigated the role of gut microbiota in CRS-induced hyperalgesia gender-specifically through 16 S ribosomal RNA (16 S rRNA) gene sequencing and untargeted metabolomic analysis using liquid chromatography-mass spectrometry (LC-MS). The study found that both male and female mice experienced hyperalgesia after CRS and antibiotic treatment. 16 S rRNA gene sequencing reveals gender differences in the fecal microbiota induced by CRS. The pain threshold decreased after transplanting the fecal microbiota from the male and female CRS group to the corresponding pseudo-germ-free mice. In addition, this study detected gender differences in the host gut microbiota and serum metabolism induced by fecal microbiota transplantation (FMT). Specifically, the different serum metabolites between the pseudo-germ-free mice receiving FMT from the CRS group and those from the control group were mainly involved in bile secretion and steroid hormone biosynthesis for male mice, and in taurine and hypotaurine metabolism and tryptophan metabolism for female mice. In summary, the gut microbiota participates in stress-induced hyperalgesia (SIH) with gender differences by influencing the host’s gut microbiota composition and serum metabolism. Therefore, our findings provided insights into developing novel gut microbiota-associated drugs for the management of gender-specific SIH.

Integrated Transcriptomics and Metabolomics Analyses of Stress-Induced Murine Hair Follicle Growth Inhibition.

Psychological stress plays an important role in hair loss, but the underlying mechanisms are not well-understood, and the effective therapies available to regrow hair are rare. In this study, we established a chronic restraint stress (CRS)-induced hair growth inhibition mouse model and performed a comprehensive analysis of metabolomics and transcriptomics. Metabolomics data analysis showed that the primary and secondary metabolic pathways, such as carbohydrate metabolism, amino acid metabolism, and lipid metabolism were significantly altered in skin tissue of CRS group. Transcriptomics analysis also showed significant changes of genes expression profiles involved in regulation of metabolic processes including arachidonic acid metabolism, glutathione metabolism, glycolysis gluconeogenesis, nicotinate and nicotinamide metabolism, purine metabolism, retinol metabolism and cholesterol metabolism. Furthermore, RNA-Seq analyses also found that numerous genes associated with metabolism were significantly changed, such as Hk-1, in CRS-induced hair growth inhibition. Overall, our study supplied new insights into the hair growth inhibition induced by CRS from the perspective of integrated metabolomics and transcriptomics analyses.

Periaqueductal gray is required for controlling chronic stress-induced depression-like behavior

BackgroundEnduring exposure to psychological stress is associated with an elevated risk of major depressive disorder (MDD). There is an enormous need to investigate the unexplored mechanisms of MDD. We examined whether pain-free stress alters synaptic transmission, causing depression-like behaviors in the ventrolateral periaqueductal gray (vlPAG), a brain stem nucleus that controls stress-related depression-like behavior. MethodsIn the current study, we studied neuronal changes in the vlPAG and behavioral transforms using electrophysiological recordings, behavioral tests, and pharmacological approaches. ResultsWe found that chronic restraint stress (CRS) diminished glutamatergic transmission in the vlPAG, leading to maladaptive behavioral despair and anhedonia in mice demonstrated by the forced swimming test (FST), tail suspension test (TST) and female urine sniffing test (FUST). Moreover, CRS increased behavioral hypersensitivity shown by the von Frey test. Bath perfusion with the rapid-acting antidepressant (2R,6R)-hydroxynorketamine (HNK) increased both the frequency and amplitude of miniature excitatory postsynaptic currents (mEPSCs) in vlPAG neurons in the CRS and control groups. Functionally, (2R,6R)-HNK directly enhanced the action potential firing rate in vlPAG neurons. Behaviorally, intravlPAG microinjection of (2R,6R)-HNK alleviated chronic restraint stress-induced depression-like behaviors and behavioral hypersensitivity. ConclusionsThese results demonstrate that psychological stress-elicited depression-like behavior is related to a remarkable decrease in glutamatergic transmission in the vlPAG. The maladaptive behaviors are attributed to hypoactivity of glutamatergic neurons in the vlPAG, and direct enhancement of glutamatergic neuronal activity in the vlPAG rescues depression-like behaviors. The present results prove that vlPAG is critical for controlling stress-induced depression-like behaviors through alteration of glutamatergic transmission.

The Antidepressant Effects of Resveratrol are Accompanied by the Attenuation of Dendrite/Dendritic Spine Loss and the Upregulation of BDNF/p-cofilin1 Levels in Chronic Restraint Mice.

Depression afflicts more than 300 million people worldwide, but there is currently no universally effective drug in clinical practice. In this study, chronic restraint stress (CRS)-induced mice depression model was used to study the antidepressant effects of resveratrol and its mechanism. Our results showed that resveratrol significantly attenuated depression-like behavior in mice. Consistent with behavioral changes, resveratrol significantly attenuated CRS-induced reduction in the density of dendrites and dendritic spines in both hippocampus and medial prefrontal cortex (mPFC). Meanwhile, in hippocampus and mPFC, resveratrol consistently alleviated CRS-induced cofilin1 activation by increasing its ser3 phosphorylation. In addition, cofilin1 immunofluorescence distribution in neuronal inner peri-membrane in controls, and cofilin1 diffusely distribution in the cytoplasm in CRS group were common in hippocampus. However, the distribution of cofilin1 in mPFC was reversed. Pearson's correlation analysis revealed that there was a significant positive correlation found between the sucrose consumption in sucrose preference test and the dendrite density in multiple sub-regions of hippocampus and mPFC, and a significant negative correlation between the immobility time in tail suspension test and the dendrite/dendritic spine density in several different areas of hippocampus and mPFC. P-cofilin1 was significantly positively correlated with the overall dendritic spine density in mPFC as well as with the overall dendrite density or BDNF in the hippocampus. Our results suggest that the BDNF/cofilin1 pathway, in which cofilin1 may be activated in a brain-specific manner, was involved in resveratrol's attenuating the dendrite and dendritic spine loss and behavioral abnormality.