Combined corticosterone treatment and chronic restraint stress lead to depression associated with early cognitive deficits in mice

Dapagliflozin mitigates cognitive deficits in a rat model of chronic restrained stress by addressing insulin resistance and mitochondrial dysfunction

Chronic stress is recognized as a risk factor for neurodegeneration. Sodium glucose co-transporter 2 receptors (SGLT2) have been found in various brain regions, suggesting the potential neuroprotective properties of SGLT2 inhibitors as dapagliflozin (DGF). This study aimed to investigate the effect of DGF on behavioral, and neurodegenerative changes in chronic restraint stress (CRS) as an animal model of cognitive impairment. Forty-eight male rats were allocated into four groups: Control; CRS-subjected group, rats were subjected to chronic restraint stress for 6 weeks to induce cognitive impairment; DGF-treated CRS group, dapagliflozin was given daily by oral gavage; and DGF-administered group. Behavioral tests were performed and fasting serum glucose, insulin, and corticosterone levels were measured. Hippocampal oxidative markers, insulin signaling, mitochondrial function, amyloid beta, p-tau, and brain-derived neurotrophic factor (BDNF) gene expression were evaluated. DGF significantly prevented CRS-induced cognitive dysfunction (Y maze and Morris water maze tests). Also, DGF ameliorated hippocampal neurodegenerative changes by decreasing tau and amyloid beta levels, while increasing BDNF gene expression. DGF reduced hippocampal phosphorylated mammalian target of rapamycin (p-mTOR) and protein kinase B (p-Akt) levels. In addition to its antioxidant effects, DGF increased ATP levels and cytochrome C oxidase activity. These findings were confirmed by transmission electron microscopic (TEM) examination. The current study demonstrates a biological link between chronic stress, insulin resistance, and cognitive impairment. Dapagliflozin has therapeutic potential in alleviating cognitive deficits and neurodegeneration primarily due to its insulin-sensitizing and antioxidant properties, along with its capacity to enhance mitochondrial function.

The leptin/BDNF/TrkB signaling pathway improves corticosteroid combined with chronic restraint stress-induced depressive-like behavior in mice

This study explored the effect and mechanism of leptin on depressive-like behavior induced by chronic corticosterone injections combined with chronic restraint stress (CORT-CRS) in mice. Differentially expressed genes (DEGs) were extracted using the Gene Expression Omnibus database and Sangerbox tool. Construct protein-protein interaction networks of target DEGs using Cytoscape software, and hub genes brain-derived neurotrophic factor (BDNF) were identified. A mouse model of depression was established using CORT-CRS. Behavioral changes were detected in the mice using the tail suspension, forced swimming, sugar water preference (SPT), and open field tests (OFT). Serum inflammatory factors were measured by Enzyme-linked immunosorbent assay (ELISA). Western blotting was used to detect the protein expression levels of BDNF and tyrosine kinase receptor B (TrkB). Immunofluorescence was used to detect hippocampal neurogenesis in each mouse group. Compared with the control group, mice in the CORT-CRS group presented with marked depression-like behavior and a higher interleukin (IL) -6, IL-1 β, tumor necrosis factor alpha (TNF - α) concentration. Different doses of leptin reversed depressive-like behavior in the CORT-CRS model mice, with significantly increased levels of BDNF, TrkB protein expression (P < 0.01). Furthermore, leptin promoted hippocampal neurogenesis in CORT-CRS-treated mice in vivo. Consequently, leptin alleviates CORT-CRS-induced depression-like behavior in mice by stimulating hippocampal neurogenesis. One possible mechanism could be related to the activation of the BDNF/TrkB signaling pathway, which could pave way for novel therapeutic targets that can be explored to prevent and treat depression.

Effect of chronic corticosterone administration on acute stress-mediated gene expression in the cortex and hippocampus of male mice

Corticosterone plays an important role in the stress response, physiological regulation, and development of stress-related psychiatric disorders. Although several studies have demonstrated that chronic corticosterone induces anxiety- or depressive-related behaviors in mice, it remains unclear whether chronic corticosterone administration affects gene expression in the brain during the stress response. This study investigated whether chronic corticosterone administration has a significant effect on stress-related gene expression in the brain. Therefore, mice were chronically treated with corticosterone in drinking water and gene expression was analyzed by quantitative PCR (qPCR). Moreover, restraint stress was acutely applied as a novel stressor in mice chronically treated with corticosterone in the cortex and hippocampus. We initially found that chronic corticosterone administration altered glucocorticoid signaling-mediated gene expression, such as FK506 binding protein 5 (Fkbp5) and glucocorticoid-inducible kinase 1 (Sgk1), in the cortex and hippocampus of mice. Next, we found that restraint stress exposure elevated Fkbp5 expression in the vehicle group; however, chronic corticosterone administration occluded further induction of Fkbp5 expression after restraint stress exposure. In addition, pro-inflammatory cytokines tumor necrosis factor α (Tnfa) and interleukin-1β (Il1b) mRNA expression in the cortex and hippocampus were remarkably enhanced by restraint stress in corticosterone-treated mice, but not in the vehicle group. Collectively, our results demonstrated that chronic corticosterone administration modulates glucocorticoid signaling and uncovered the robust induction of pro-inflammatory cytokines after restraint stress exposure in chronically corticosterone-treated mice. These mechanisms may be involved in the molecular basis for the onset of stress-related mental illnesses.

Combined Restraint Stress and Metal Exposure Paradigms in Rats: Unravelling Behavioural and Neurochemical Perturbations

Accumulation of heavy metals (Mn and Ni) and prolonged exposure to stress are associated with adverse health outcomes. Various studies have shown the impacts of stress and metal exposures on brain function. However, no study has examined the effects of co-exposure to stress, Mn, and Ni on the brain. This study addresses this gap by evaluating oxidative and glial responses, apoptotic activity, as well as cognitive processes in a rat model. Adult Wistar rats were exposed to vehicle (control), restraint stress, 25 mg/kg of manganese (Mn) or nickel (Ni), or combined restraint stress plus Mn or Ni. Following treatment, rats were subjected to several behavioural paradigms to assess cognitive function. Enzyme activity, as well as ATPase levels, were evaluated. Thereafter, an immunohistochemical procedure was utilised to evaluate neurochemical markers of glial function, myelination, oxidative stress, and apoptosis in the hippocampus, prefrontal cortex (PFC), and striatum. Results showed that stress and metal exposure increased oxidative stress markers and reduced antioxidant levels. Further, combined stress and metal exposure reduced various forms of learning and memory ability in rats. In addition, there were alterations in Iba1 activity and Nrf2 levels, reduced Olig2 and myelin basic protein (MBP) levels, and increased caspase-3 expression. These neurotoxic outcomes were mostly exacerbated by co-exposure to stress and metals. Overall, our findings establish that stress and metal exposures impaired cognitive performance, induced oxidative stress and apoptosis, and led to demyelination effects which were worsened by combined stress and metal exposure.

Postbiotics Made From Selected Lactic Acid Bacteria Improves Chronic Restraint Stress-Induced Anhedonia and Sleep Disorders

Sleep disorders have become one of the most prevalent neuropsychiatric disorders in recent years. This study aimed to investigate the effects of postbiotics derived from selected lactic acid bacteria on anhedonia and sleep disorders in chronic restraint stress (CRS)-induced mice, as well as their potential mechanisms. Mice were orally administered normal saline, low, medium, or high doses of postbiotics for 30 days, with CRS applied from days 1 to 21. The medium dose of postbiotics significantly increased the sucrose preference index, and the high dose of postbiotics significantly increased sleep duration. Postbiotic treatment effectively restored the diversity and composition of the gut microbiota to levels comparable to those observed in the vehicle (Veh) group. Furthermore, low and medium doses of postbiotics significantly reduced serum corticosterone levels, and medium and high doses significantly reduced serum IL-1β levels. Additionally, postbiotics administration significantly increased glutamate and GABA levels in both the prefrontal cortex and hypothalamus, as well as GABA levels in the feces. These results indicate that postbiotics alleviate CRS-induced anhedonia and sleep disorders in a dose-dependent manner. This effect may be mediated through the restoration of homeostasis in the MGB axis, HPA axis, inflammation pathways, and neurotransmitter balance.

Neuropathological implication of high blood bilirubin in patients and model rats with depression

PURPOSE

Elevated bilirubin levels have been associated with major depressive disorder (MDD); however, the exact impact of bilirubin on MDD and the underlying molecular mechanisms remain unclear. Here, we explored the influence of bilirubin on MDD and sought to identify the mechanisms via which bilirubin induces depressive-like behavior.

PATIENTS AND METHODS

Forty patients who were diagnosed with MDD and received treatment with selective serotonin reuptake inhibitors (SSRIs) were included, with 43 healthy volunteers serving as controls. Clinical symptoms were evaluated using Hamilton depression rating scale-24 (HAMD-24) and the Hamilton anxiety rating scale. Serum concentrations of total bilirubin (TBIL) and indirect bilirubin (IBIL) were measured at baseline and after treatment using an automated biochemical analyzer. The connection between clinical symptoms and TBIL or IBIL was examined using Pearson correlation. Chronic restraint stress (CRS) was employed to generate a rat model of depression. TBIL, IBIL in rat serum were measured by ELISA. Reactive oxygen species (ROS) contents in rat hippocampal tissues were quantified by flow cytometry. The levels of microglial markers and the extent of neuronal damage in the rat hippocampus were assessed by immunofluorescence and transmission electron microscopy, respectively.

RESULTS

Serum TBIL and IBIL levels were higher in patients with MDD than in the healthy controls. After treatment with SSRIs, the serum levels of TBIL and IBIL in MDD patients were significantly reduced. The levels of TBIL and IBIL were associated with HAMD-24 in MDD patients. Compared with the controls, the serum levels of TBIL, IBIL and the hippocampal ROS contents were elevated in CRS-exposed rats. Fluoxetine lowered inflammatory factor levels, mitigated oxidative stress.

CONCLUSION

Our findings indicate a possible correlation between elevated serum bilirubin and depressive symptoms. Increases in ROS levels, along with neuronal damage, may represent pathological mechanisms underlying MDD.

Novel Psilocin Prodrugs with Altered Pharmacological Properties as Candidate Therapies for Treatment-Resistant Anxiety Disorders

The psychedelic prodrug psilocybin has shown therapeutic benefits for the treatment of numerous psychiatric conditions. Despite positive clinical end points targeting depression and anxiety, concerns regarding the duration of the psychedelic experience produced by psilocybin, associated with enduring systemic exposure to the active metabolite psilocin, pose a barrier to its therapeutic application. Our objective was to create a novel prodrug of psilocin with similar therapeutic benefits but a reduced duration of psychedelic effects compared with psilocybin. Here, we report the synthesis and functional screening of 28 new chemical entities. Our strategy was to introduce a diversity of cleavable groups at the 4-hydroxy position of the core indole moiety to modulate metabolic processing. We identified several novel prodrugs of psilocin with altered pharmacokinetic profiles and reduced pharmacological exposure compared with psilocybin. These candidate prodrugs have the potential to maintain the long-term benefits of psilocybin therapy while attenuating the duration of psychedelic effects.

Niuhuang Qingxin Wan ameliorates depressive-like behaviors and improves hippocampal neurogenesis through modulating TrkB/ERK/CREB signaling pathway in chronic restraint stress or corticosterone challenge mice

Introduction: Chronic stress-associated hormonal imbalance impairs hippocampal neurogenesis, contributing to depressive and anxiety behaviors. Targeting neurogenesis is thus a promising antidepressant therapeutic strategy. Niuhuang Qingxin Wan (NHQXW) is an herbal formula for mental disorders in Traditional Chinese Medicine (TCM) practice, but its anti-depressant efficacies and mechanisms remain unverified. Methods: In the present study, we tested the hypothesis that NHQXW could ameliorate depressive-like behaviors and improve hippocampal neurogenesis by modulating the TrkB/ERK/CREB signaling pathway by utilizing two depression mouse models including a chronic restraint stress (CRS) mouse model and a chronic corticosterone (CORT) stress (CCS) induced mouse model. The depression-like mouse models were orally treated with NHQXW whereas fluoxetine was used as the positive control group. We evaluated the effects of NHQXW on depressive- and anxiety-like behaviors and determined the effects of NHQXW on inducing hippocampal neurogenesis. Results: NHQXW treatment significantly ameliorated depressive-like behaviors in those chronic stress mouse models. NHQXW significantly improved hippocampal neurogenesis in the CRS mice and CCS mice. The potential neurogenic mechanism of NHQXW was identified by regulating the expression levels of BDNF, TrkB, p-ERK (T202/T204), p-MEK1/2 (S217/221), and p-CREB (S133) in the hippocampus area of the CCS mice. NHQXW revealed its antidepressant and neurogenic effects that were similar to fluoxetine. Moreover, NHQXW treatment revealed long-term effects on preventing withdrawal-associated rebound symptoms in the CCS mice. Furthermore, in a bioactivity-guided quality control study, liquiritin was identified as one of the bioactive compounds of NHQXW with the bioactivities of neurogenesis-promoting effects. Discussion: Taken together, NHQXW could be a promising TCM formula to attenuate depressive- and anxiety-like behaviors against chronic stress and depression. The underlying anti-depressant mechanisms could be correlated with its neurogenic activities by stimulating the TrkB/ERK/CREB signaling pathway.

Capparis sepiaria's root bark aqueous lyophilisate shows antiamnesic properties on scopolamine induce cognitive impairment in mice

Capparis sepiaria (Capparaceae) is a plant used in African traditional medicine to treat psychiatic disorders. The aim of this study was to assess the anti-amnesic effect of aqueous lyophilisate of the root bark of Capparis sepiaria (C. sepiaria) on scopolamine-induced animal model of memory impairment using Swiss albino adult mice of both sexes. Memory integrity was assessed by Morris water Maze test, Novel Object Recognition (NOR) and Object-location memory (OLT) tasks were used to assess behavioural components of memory processes and learning. Malondialdehyde (MDA), reduced glutathione (GSH), NO levels and catalase were used to assess oxidative stress while acethylcholinesterase activity was used to evaluate acetylcholine activity in the hippocampus tissues. The quantitative phytochemistry and acute toxicity of the roots of C. sepiaria were also evaluated. The aqueous lyophilisate of C. sepiaria at doses of 10 mg/kg and 40 mg/kg significantly increased the discrimination index in the Morris Water Maze and the objet location tasks. The aqueous lyophilisate of C. sepiaria significantly increased hippocampal GSH and catalase levels and decreased hippocampal MDA, NO levels and achetylcholinesterase (AChE) activities. The aqueous lyophilisate of C. sepiaria showed no acute toxicity with a LD50 > 5000 mg/kg, and revealed a content of flavonoids, tannins and phenols. These results suggest that C. sepiaria improve memory impairment induced by scopolamine and therefore possess antiamnesic properties. These properties would result from a modulation of cholinergic neurotransmission as well as an antioxidant activity of the plant.

Alteration of the α5 GABA receptor and 5HTT lead to cognitive deficits associated with major depressive-like behaviors in a 14-day combined stress rat model

INTRODUCTION

Current models used to study the pathophysiology of major depressive disorder (MDD) are laborious and time consuming. This study examined the effect of a 14-day combined stress model (CS; corticosterone injection and restraint stress) in male Sprague-Dawley rats and also compare the effect of CS versus 28-day corticosterone treatment on depressive-like behaviour and cognitive deficits.

MATERIEL AND METHODS

Depressive-like behaviours and cognitive deficits were assessed in the forced swim test (FST), sucrose preference (SPT), Morris water maze (MWM) and novel object recognition (NORT) tests. Real-time PCR and ELISA were respectively used to detect expression of the serotonin transporter (5-HTT), serotonin 1 A receptor (5-HT1A), α5 GABAA receptor, and the concentrations of corticosterone (plasma), GABA and acetylcholinesterase (AChE) in the hippocampus and Prefrontal cortex (PFC).Results CS group showed increased immobility time in the FST, time to reach the MWM platform, higher corticosterone level, and increased expressions of hippocampal and PFC 5-HT1A and α5 GABAA receptors, and AChE compared to their control groups. In contrast, reductions in SPT ratio, discrimination index in NORT, time in target quadrant, and hippocampal 5-HTT expression was noted relative to their control group. Compared to the 28-day corticosterone only group, PFC 5-HT1A, Hippocampal 5-HTT were reduced, while PFC 5-HTT, Hippocampal α5 GABAA receptors, and AChE concentrations were higher in the CS group.

CONCLUSION

Our CS model induced depressive-like behaviour with early cognitive deficits in rats affecting both hippocampus and PFC. The CS model may be useful in investigating new and comprehensive treatment strategies for MDD.

Memory Recovery Effect of a New Bioactive Innovative Combination in Rats with Experimental Dementia

Alzheimer's disease manifests as a complex pathological condition, with neuroinflammation, oxidative stress and cholinergic dysfunction being a few of the many pathological changes. Due to the complexity of the disease, current therapeutic strategies aim at a multitargeted approach, often relying on a combination of substances with versatile and complementary effects. In the present study, a unique combination of α-lipoic acid, citicoline, extracts of leaves from olive tree and green tea, vitamin D3, selenium and an immune-supporting complex was tested in scopolamine-induced dementia in rats. Using behavioral and biochemical methods, we assessed the effects of the combination on learning and memory, and elucidated the mechanisms of these effects. Our results showed that, compared to its components, the experimental combination was most efficient in improving short- and long-term memory as assessed by the step-through method as well as spatial memory as assessed by T-maze and Barnes maze underlined by decreases in AChE activity (p < 0.05) and LPO (p < 0.001), increases in SOD activity in the cortex (p < 0.05) and increases in catalase (p < 0.05) and GPx (p < 0.01) activities and BDNF (p < 0.001) and pCREB (p < 0.05) levels in the hippocampus. No significant histopathological changes or blood parameter changes were detected, making the experimental combination an effective and safe candidate in a multitargeted treatment of AD.

Cashew (Anacardium occidentale) Extract: Possible Effects on Hypothalamic-Pituitary-Adrenal (HPA) Axis in Modulating Chronic Stress

Depression presents a significant global health burden, necessitating the search for effective and safe treatments. This investigation aims to assess the antidepressant effect of the hydroethanolic extract of Anacardium occidentale (AO) on depression-related behaviors in rats. The depression model involved 42 days of unpredictable chronic mild stress (UCMS) exposure and was assessed using the sucrose preference and the forced swimming (FST) test. Additionally, memory-related aspects were examined using the tests Y-maze and Morris water maze (MWM), following 21 days of treatment with varying doses of the AO extract (150, 300, and 450 mg/kg) and Imipramine (20 mg/kg), commencing on day 21. The monoamines (norepinephrine, serotonin, and dopamine), oxidative stress markers (MDA and SOD), and cytokines levels (IL-1β, IL-6, and TNF-α) within the brain were evaluated. Additionally, the concentration of blood corticosterone was measured. Treatment with AO significantly alleviated UCMS-induced and depressive-like behaviors in rats. This was evidenced by the ability of the extract to prevent further decreases in body mass, increase sucrose consumption, reduce immobility time in the test Forced Swimming, improve cognitive performance in both tests Y-maze and the Morris water maze by increasing the target quadrant dwelling time and spontaneous alternation percentage, and promote faster feeding behavior in the novelty-suppressed feeding test. It also decreased pro-inflammatory cytokines, corticosterone, and MDA levels, and increased monoamine levels and SOD activity. HPLC-MS analysis revealed the presence of triterpenoid compounds (ursolic acid, oleanolic acid, and lupane) and polyphenols (catechin quercetin and kaempferol). These results evidenced the antidepressant effects of the AO, which might involve corticosterone and monoaminergic regulation as antioxidant and anti-inflammatory activities.

Memory impairments in rodent depression models: A link with depression theories

More than 80% of depressed patients struggle with learning new tasks, remembering positive events, or concentrating on a single topic. These neurocognitive deficits accompanying depression may be linked to functional and structural changes in the prefrontal cortex and hippocampus. However, their mechanisms are not yet completely understood. We conducted a narrative review of articles regarding animal studies to assess the state of knowledge. First, we argue the contribution of changes in neurotransmitters and hormone levels in the pathomechanism of cognitive dysfunction in animal depression models. Then, we used numerous neuroinflammation studies to explore its possible implication in cognitive decline. Encouragingly, we also observed a positive correlation between increased oxidative stress and a depressive-like state with concomitant memory deficits. Finally, we discuss the undeniable role of neurotrophin deficits in developing cognitive decline in animal models of depression. This review reveals the complexity of depression-related memory impairments and highlights the potential clinical importance of gathered findings for developing more reliable animal models and designing novel antidepressants with procognitive properties.

Characteristic Features of Deep Brain Lymphatic Vessels and Their Regulation by Chronic Stress

Studies have demonstrated that a functional network of meningeal lymphatic vessels exists in the brain. However, it is unknown whether lymphatic vessels could also extend deep into the brain parenchyma and whether the vessels could be regulated by stressful life events. We used tissue clearing techniques, immunostaining, light-sheet whole-brain imaging, confocal imaging in thick brain sections and flow cytometry to demonstrate the existence of lymphatic vessels deep in the brain parenchyma. Chronic unpredictable mild stress or chronic corticosterone treatment was used to examine the regulation of brain lymphatic vessels by stressful events. Western blotting and coimmunoprecipitation were used to provide mechanistic insights. We demonstrated the existence of lymphatic vessels deep in the brain parenchyma and characterized their features in the cortex, cerebellum, hippocampus, midbrain, and brainstem. Furthermore, we showed that deep brain lymphatic vessels can be regulated by stressful life events. Chronic stress reduced the length and areas of lymphatic vessels in the hippocampus and thalamus but increased the diameter of lymphatic vessels in the amygdala. No changes were observed in prefrontal cortex, lateral habenula, or dorsal raphe nucleus. Chronic corticosterone treatment reduced lymphatic endothelial cell markers in the hippocampus. Mechanistically, chronic stress might reduce hippocampal lymphatic vessels by down-regulating vascular endothelial growth factor C receptors and up-regulating vascular endothelial growth factor C neutralization mechanisms. Our results provide new insights into the characteristic features of deep brain lymphatic vessels, as well as their regulation by stressful life events.

Antidepressant, anti-amnesic and vasoprotective effect of Bombax costatum Pellegr. & Vuillet aqueous stem bark extract on chronic mild unpredictable stress induced in rat

ETHNOPHARMACOLOGICAL RELEVANCE

Bombax costatum Pellegr. & Vuillet is used traditionally in Northern Cameroon to treat memory impairment, anxiety, insomnia and depression.

AIM OF THE STUDY

Investigating the effect of Bombax costatum stem bark aqueous extract (BC) on depression associated with amnesia and vascular disorder, using a chronic mild unpredictable stress (CMUS) model in rats for 30 days.

MATERIALS AND METHODS

Sucrose Preference Test (SPT), Forced Swimming Test (FST), corticosteronemia, brain serotonin and dopamine level were evaluated as indices of antidepressant-like effect. The Novel Object Recognition Task (NOR), the Morris Water Maze (MWM) and acetylcholinesterase activity in the hippocampus were also used to verify memory integrity. Oxidative and nitrosative stress markers, the lipid profile and atherogenic index were estimated in blood serum to assess vasoprotective effect. Chlorophenylalanine and haloperidol, were used to delineate the extract's mechanism of action.

RESULTS

CMUS induced a decrease in sucrose preference and swimming time in the SPT and FST respectively while BC (27.5 and 55 mg/kg) increased sucrose preference and swimming time. Increments in these parameters were however reversed by the treatment of rats with chlorophenylalanine a serotonin synthesis inhibitor and haloperidol a D2 receptor antagonist. An increase in blood corticosterone level, prefrontal cortex malondialdehyde and nitric oxide concentrations were reversed by the extract. Moreover, BC increased the time spent in the target quadrant of the MWM test and the discrimination index in the NOR test. This was associated with an increase in hippocampus superoxide dismutase and catalase levels, a decrease in acetylcholine esterase level, total blood cholesterol and atherogenicity index compared to CMUS group.

CONCLUSION

Thirty days CMUS induces a depressive state in rats. BC reverses this condition when administered alongside stress exposure. This antidepressive effect is associated with antiamnesic, antioxidant and vasoprotective actions, suggesting its use as a potential candidate in the management of major depressive disorder.

Magnetic resonance imaging features of hippocampus and mechanism of neurocognitive dysfunction for antiepileptic drugs in treatment of depression rats

To explore the effects of antiepileptic drug sodium valproate on magnetic resonance imaging (MRI) images, neurological cognition, and JAK1/STAT3 pathway in hippocampus of rats with depression, 30 Sprague Dawley (SD) rats were included. The depression model (DM) was prepared through the chronic stress restraint test. Some model rats were injected with 10 mg/kg sodium valproate into abdominal cavity before modeling (RT group)), and healthy rats were selected as controls (healthy control (HC) group). Depth of split brain was greatly increased in DM group, and nitrogen-acetyl aspartic acid (NAA)/creatine (Cr), glutamic acid (Glu)/Cr, and choline (Cho)/Cr ratios were greatly reduced (P < 0.05). Behavioral test results showed that sugar water preference rate, escape latency, and divergence index in DM group were greatly reduced (P < 0.05), and cumulative immobility time, target quadrant stay time, and number of crossings in forced swimming and tail suspension were prolonged dramatically (P < 0.05), with no difference between the two groups (P > 0.05). Expression levels of interleukin 1β (IL-1β) and interleukin 6 (IL-6) in hippocampus of DM group were obviously increased (P < 0.05), and expression levels of JAK1 and STAT3 were decreased visibly (P < 0.05), with no difference between the two (P > 0.05). In summary, anti-epileptic drug sodium valproate effectively improves hippocampal volume characteristics and memory and neurocognitive dysfunction of depression models.

Defining Valid Chronic Stress Models for Depression With Female Rodents

Women are twice as likely to experience depression than men, yet until recently, preclinical studies in rodents have focused almost exclusively on males. As interest in sex differences and sex-specific mechanisms of stress susceptibility increases, chronic stress models for inducing depression-relevant behavioral and physiological changes in male rodents are being applied to females, and several new models have emerged to include both males and females, yet not all models have been systematically validated in females. An increasing number of researchers seek to include female rodents in their experimental designs, asking the question "what is the ideal chronic stress model for depression in females?" We review criteria for assessing female model validity in light of key research questions and the fundamental distinction between studying sex differences and studying both sexes. In overviewing current models, we explore challenges inherent to establishing an ideal female chronic stress model, with particular emphasis on the need for standardization and adoption of validated behavioral tests sensitive to stress effects in females. Taken together, these considerations will empower female chronic stress models to provide a better understanding of stress susceptibility and allow the development of efficient sex-specific treatments.

Adiponectin Mediates the Protection of H2S Against Chronic Restraint Stress-Induced Cognitive Impairment via Attenuating Hippocampal Damage

Emerging evidence shows that chronic restraint stress (CRS) can induce cognitive dysfunction, which involves in hippocampal damage. Our recent research reveals that hydrogen sulfide (H2S), a novel gasotransmitter, protects against CRS-induced cognitive impairment, but the underlying mechanism remains unclear. Adiponectin, the most abundant plasma adipokine, has been shown to elicit neuroprotective property and attenuate cognitive impairment. Hence, the present work was aimed to explore whether adiponectin mediates the protective effect of H2S on CRS-induced cognitive impairment by inhibiting hippocampal damage. Results found that administration of Anti-Acrp30, a neutralizing antibody of adiponectin, obviously reverses sodium hydrosulfide (NaHS, an exogenous H2S donor)-induced the inhibition on CRS-induced cognitive impairment according to Y-maze test, Novel object recognition (NOR) test, and Morris water maze (MWM) test. In addition, Anti-Acrp30 blocked the protective effect of NaHS on hippocampal apoptosis in rats-subjected with CRS as evidenced by the pathological changes in hippocampus tissues in hematoxylin and eosin (HE) staining and the increases in the amount of the condensed and stained to yellowish-brown or brownish yellow neuron nucleuses in terminal deoxynucleotidyl transferase transfer-mediated dUTP nick end-labeling (TUNEL) staining as well as the expression of hippocampal pro-apoptotic protein (Bax), and a decrease in the expression of hippocampal anti-apoptotic protein (Bcl-2). Furthermore, Anti-Acrp30 mitigated the inhibitory effect of NaHS on CRS-induced oxidative stress as illustrated by the up-regulation of malondialdehyde (MDA) content and the down-regulation of superoxide dismutase (SOD) activity and glutathione (GSH) level in the hippocampus. Moreover, Anti-Acrp30 eliminated NaHS-induced the reduction of endoplasmic reticulum (ER) stress-related proteins including binding immunoglobulin protein (BIP), C/EBP homologous protein (CHOP), and Cleaved Caspase-12 expressions in the hippocampus of rats-exposed to CRS. Taken together, these results indicated that adiponectin mediates the protection of H2S against CRS-induced cognitive impairment through ameliorating hippocampal damage.

Ginsenoside Re protects against chronic restraint stress-induced cognitive deficits through regulation of NLRP3 and Nrf2 pathways in mice

Exposure to chronic stress negatively affects the development of cognition, characterized by learning and memory decline. Ginsenoside Re (GRe), an active compound derived from Panax ginseng, exhibited neuroprotective activity in various neurological diseases. In this study, the protective effect of GRe on chronic restraint stress (CRS)-induced memory deficit was investigated. The mice were experienced 35 days of the CRS induction. The GRe was administered daily orally (10, 20, or 40 mg/kg) during the next 3 weeks stress session and the behavior test period. The CRS-induced memory impairment mice were subjected to behavioral tasks, such as the Y-maze, novel objects recognition, and step-through passive avoidance tests. Nissl staining was used to examine the neuron numbers. The levels of antioxidant enzymes, malondialdehyde, and proinflammatory factor were determined by kits and ELISA assays. The expressions of brain-derived neurotrophic factor (BDNF), NOD-like receptor protein 3 (NLRP3), nuclear factor erythroid-2 related factor 2 (Nrf2) and synapse-associated proteins (synaptophysin, SYP, and postsynaptic density 95, PSD95) were measured by Western blotting. Behavioral assessments indicated that GRe could ameliorate the cognitive impairment of CRS-induced mice, as indicated by increased responses in Y-maze (p < .05), novel objects recognition (p < .01), and step-through passive avoidance tests (p < .01). In addition, GRe treatment significantly decreased the neuronal loss in CRS mice in histological examination. Moreover, chronic GRe treatment significantly ameliorated the down-regulated the expressions of BDNF, Nrf2, heme oxygenase (HO)-1, SYP, and PSD95, as well as up-regulated NLRP3, the adaptor protein ASC, and Caspase-1 protein expression in the hippocampus of CRS-treated mice. Taken together, these findings suggest that GRe has a potential therapeutic effect on memory impairment in C57BL/6J mice exposed to CRS paradigm.

PTEN in prefrontal cortex is essential in regulating depression-like behaviors in mice

Chronic stress is an environmental risk factor for depression and causes neuronal atrophy in the prefrontal cortex (PFC) and other brain regions. It is still unclear about the molecular mechanism underlying the behavioral alterations and neuronal atrophy induced by chronic stress. We here report that phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a mediator for chronic stress-induced depression-like behaviors and neuronal atrophy in mice. One-month chronic restraint stress (CRS) up-regulated PTEN signaling pathway in the PFC of mice as indicated by increasing levels of PTEN, p-MEK, and p-ERK but decreasing levels of p-AKT. Over-expression of Pten in the PFC led to an increase of depression-like behaviors, whereas genetic inactivation or knockdown of Pten in the PFC prevented the CRS-induced depression-like behaviors. In addition, systemic administration of PTEN inhibitor was also able to prevent these behaviors. Cellular examination showed that Pten over-expression or the CRS treatment resulted in PFC neuron atrophy, and this atrophy was blocked by genetic inactivation of Pten or systemic administration of PTEN inhibitor. Furthermore, possible causal link between Pten and glucocorticoids was examined. In chronic dexamethasone (Dex, a glucocorticoid agonist) treatment-induced depression model, increased PTEN levels were observed, and depression-like behaviors and PFC neuron atrophy were attenuated by the administration of PTEN inhibitor. Our results indicate that PTEN serves as a key mediator in chronic stress-induced neuron atrophy as well as depression-like behaviors, providing molecular evidence supporting the synaptic plasticity theory of depression.

Neuroscience education and research in Cameroon: Current status and future direction

Neurological disorders comprise 20% of hospital admissions in Cameroon. The burden of neurological disorders is increasing, especially in children and the elderly. However, there are very few neurologists, psychiatrists, gerontologists and neuropsychologists trained in the treatment of neurological disorders in Cameroon and there are very few facilities for training in basic and clinical neuroscience. Although non-governmental organizations such as the International Brain Research Organization (IBRO), International Society of Neurochemistry (ISN), and Teaching and Research in Natural Sciences for Development (TReND) in Africa have stepped in to provide short training courses and workshops in neuroscience, these are neither sufficient to train African neuroscientists nor to build the capacity to train neuroscience researchers and clinicians. There has also been little support from universities and the government for such training. While some participants of these schools have managed to form collaborations with foreign researchers and have been invited to study abroad, this does not facilitate the training of neuroscientists in Cameroon. Moreover, the research infrastructure for training in neuroscience remains limited. This is reflected in the low research output from Cameroonian universities in the field. In this review, we describe the burden of neurological disorders in Cameroon and outline the outstanding efforts of local scientists to develop the discipline of neuroscience, which is still an emerging field in Cameroon. We identify key actionable steps towards the improvement of the scientific capacity in neuroscience in Cameroon: (1) develop targeted neuroscience training programs in all major universities in Cameroon; (2) implement a thriving scientific environment supported by international collaborations; (3) focus on the leadership and the mentorship of both local and senior neuroscientists; (4) develop public awareness and information of policy makers to increase governmental funding for neuroscience research.

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Improving scientific capacity to tackle the neurological diseases burden in Cameroon is urgent.

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Neuroscience schools and advocated researchers shape the future of neuroscience in Cameroon.

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Public-private partnerships are required for sustainable country impact of neuroscience schools.

Antidepressant and anti-amnesic effects of the aqueous lyophilisate of the leaves of Leptadenia arborea on an animal model of cognitive deficit associated depression

Leptadenia arborea (Asclepiadaceae) is a plant used in traditional medicine to treat syphilis, migraine, and mental illnesses. The aim of our study was to investigate possible antidepressant and anti-amnesic effects of the aqueous lyophilisate of the leaves of Leptadenia arborea in an animal model of cognitive deficit associated depression. Swiss albino adult mice of both sexes were used for this study. A 14-day combined stress model was used to induce depression with early cognitive deficits. The forced swimming test, the open field test and plasma corticosterone level were used to assess antidepressant-like effect. The novel object recognition task (NORT), the Morris Water Maze (MWM) and neurochemical analysis of hippocampal acetylcholinesterase activity was also carried out to assess memory integrity. The aqueous lyophelisate of L. arborea increased swimming time and decreased immobility time in the forced swimming test. In the open field test they was no difference in the number of lines crossed between groups, and the lyophilisate-treated mice spent more time in the centre compared to the control. The lyophilisate decreased the plasma level of corticosterone compared to the control. The lyophilisate decreased the latency to reach the hidden platform and increased the time spent in the target quadrant in the MWM. The lyophilisate also increased the time of exploration of the novel object in the NORT and decreased the acetylcholinesterase activity in the hippocampus. L. arborea effects were decreased when it was co-administered with pCPA. Results suggest that the aqueous lyophilisate of the leaves of L. arborea possess antidepressant-like and anti-amnesic effects.

Ginsenoside Rd reverses cognitive deficits by modulating BDNF-dependent CREB pathway in chronic restraint stress mice

Cognitive impairment has been widely recognized as a common symptom of chronic stress. Ginsenoside Rd (GRd), the major active compound in Panax ginseng, was previously reported in various neurological researches. However, little research is available regarding on the effect of GRd on cognitive improvement in mice subjected to chronic stress. In the present study, we investigated the neuroprotective effects of GRd in chronic restraint stress (CRS)-induced cognitive deficits and explored the potential mechanism in male C57BL/6J mice. Our results demonstrated that oral administration of GRd for 28 days markedly increased the spontaneous alternation in Y-maze and the relative discrimination index in novel object or location recognition tests following CRS. Additionally, GRd treatment considerably increased the antioxidant enzymes activities in the hippocampus. The expression levels of hippocampus and serum inflammation factors in the CRS groups were also counter-regulated by GRd treatment. Meanwhile, GRd treatment could reverse CRS-induced the decrease in phosphorylated phosphoinositide 3-kinase (PI3K), camp-reflecting element binding protein (CREB), brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (TrkB) expression in the hippocampus. These findings provided evidences that GRd improves cognitive impairment in CRS mice by mitigating oxidative stress and inflammation, while upregulating the hippocampal BDNF-mediated CREB signaling pathway.

Chronic restraint stress increases social interaction in C57BL/6J mice monitoring through MiceProfiler analysis

The social deficit is a prevailing symptom in stress-induced depression. Although social interaction behavior has been widely studied in humans and rodents, it is imprecise to record the social behavior between two free-moving mice via perusal. In the present study, we applied an approach to analyze the social behavior in mice using a software named "MiceProfiler." C57BL/6J mice were stressed via chronic restraint stress (CRS) and housed in three populations of different sizes as follows: single, three in a cage, and six in a cage. The MiceProfiler was used to analyze the video of behavioral repertoire and, the result showed that stressed and single housed mice exhibited more social interaction both in the contact time and contact activities. Furthermore, we investigated the effect of CRS on social behavior when the mice were housed in larger populations size (three or six in a cage) and found that, the CRS procedure promoted social interaction. However, the larger population size resulted in the less total contact time, less time of head-tail, and moving in an opposite way. Besides, the CRS mice showed less social avoidance while the mice from a larger population presented less active contact. And the CRS mice also exhibited a higher social hierarchy compared with the control. Our data indicated that mild restraint stress might increase the intercommunication between mice. Collectively, our findings provided a new evidence for social behavior study and the MiceProfiler could be a new tool to measure the social behaviors of rodents.

Corticosterone Induced the Increase of proBDNF in Primary Hippocampal Neurons Via Endoplasmic Reticulum Stress

Major depression disorder is one of the most common psychiatric disorders that greatly threaten the mental health of a large population worldwide. Previous studies have shown that endoplasmic reticulum (ER) stress plays an important role in the pathophysiology of depression, and current research suggests that brain-derived neurotrophic factor precursor (proBDNF) is involved in the development of depression. However, the relationship between ER and proBDNF in the pathophysiology of depression is not well elucidated. Here, we treated primary hippocampal neurons of mice with corticosterone (CORT) and evaluated the relationship between proBDNF and ERS. Our results showed that CORT induced ERS and upregulated the expression of proBDNF and its receptor, Follistatin-like protein 4 (FSTL4), which contributed to significantly decreased neuronal viability and expression of synaptic-related proteins including NR2A, PSD95, and SYN. Anti-proBDNF neutralization and ISRIB (an inhibitor of the ERS) treatment, respective ly, protected neuronal viabilities and increased the expression of synaptic-related proteins in corticosterone-exposed neurons. ISRIB treatment reduced the expression of proBDNF and FSTL4, whereas anti-proBDNF treatment did not affect ERS markers (Grp78, p-PERK, ATF4) expression. Our study presented evidence that CORT-induced ERS negatively regulated the neuronal viability and the level of synaptic-related protein of primary neurons via the proBDNF/FSTL4 pathway.

Effects of corticosterone injections in mid-to-late mouse postnatal development on adult motor activity and coordination

Glucocorticoids are involved in the developing brain but, in excessive amounts, may depress its growth and cause psychomotor development disorders. To test the long-term vulnerability of motor structures such as the cerebellum to supraphysiological corticosterone (CORT), the hormone was subcutaneously delivered at a dose of 20 mg/kg from postnatal day (P) 8 to P29 in C57BL/6 male mice evaluated for sensorimotor functions at P15, P22, P29, and 3 months. Relative to placebo, CORT increased motor activity in the open-field at P29 and 3 months as well as facilitating rotorod acquisition and visuomotor control necessary for swimming towards a visible goal without affecting spatial learning in the Morris water maze. CORT caused lobule-specific effects on cerebellar morphology by decreasing granule cell layer thickness in simplex lobule but increasing molecular and granule cell layer thickness in crus 2. The functional impact of these changes is indicated by significant correlations found between cerebellar size and activity levels or proficiency on the rotorod test of motor coordination.

Chaihu-Shugan-San Reinforces CYP3A4 Expression via Pregnane X Receptor in Depressive Treatment of Liver-Qi Stagnation Syndrome

Backgrounds. Chaihu-Shugan-San (CSS) is a classic traditional Chinese herbal prescription for treating depression. However, the underlying mechanism of the Chinese syndrome-specific efficacy of CSS is poorly understood. Aim of the Study. From traditional Chinese medicine and pharmacogenetics perspectives, the present study aimed to investigate the antidepressant effects of CSS on a mouse model of Liver-Qi Stagnation (LQS) syndrome and its underlying mechanisms. Methods and Materials. We used two main mouse models of depressive syndromes in the study, including LQS and liver stagnation and spleen deficiency (LSSD) syndrome. Tail suspension and forced swimming tests were used to evaluate the effects of CSS on animal behaviour. The expression level of the CYP450 enzyme from liver microsomes was analysed by western blot (WB) analysis and quantitative real-time polymerase chain reaction (qRT-PCR). More specifically, we analysed the key compounds of CSS that are responsible for CYP450 regulation via bioinformatics. Ultimately, luciferase assays were employed to confirm the prediction in vitro. Results. CSS remarkably reduced the immobile time in LQS rather than in LSSD mice. Although CSS significantly upregulated CYP2C9 in mice with both syndromes, activated translation of CYP3A4 induced by CSS was only observed in the LQS group. Bioinformatics analysis revealed that the unique regulation of CYP3A4 was responsible for the effects of glycyrrhetinic acid (GA) from CSS. Further luciferase assays confirmed the enhancement of CYP3A4 expression via the pregnane X receptor (PXR) pathway in vitro. Conclusions. CSS specifically upregulates the translation of CYP3A4 via the PXR pathway in depressed LQS mice. GA, a bioactive compound that originates from CSS, contributes to this activation. This work provides novel insight into Chinese syndrome-based therapy for depression.

Advance in Stress for Depressive Disorder

Stress is an adaptive response to environment aversive stimuli and a common life experience of one's daily life. Chronic or excessive stress especially that happened in early life is found to be deleterious to individual's physical and mental health, which is highly related to depressive disorders onset. Stressful life events are consistently considered to be the high-risk factors of environment for predisposing depressive disorders. In linking stressful life events with depressive disorder onset, dysregulated HPA axis activity is supposed to play an important role in mediating aversive impacts of life stress on brain structure and function. Increasing evidence have indicated the strong association of stress, especially the chronic stress and early life stress, with depressive disorders development, while the association of stress with depression is moderated by genetic risk factors, including polymorphism of SERT, BDNF, GR, FKBP5, MR, and CRHR1. Meanwhile, stressful life experience particularly early life stress will exert epigenetic modification in these risk genes via DNA methylation and miRNA regulation to generate long-lasting effects on these genes expression, which in turn cause brain structural and functional alteration, and finally increase the vulnerability to depressive disorders. Therefore, the interaction of environment with gene, in which stressful life exposure interplay with genetic risk factors and epigenetic modification, is essential in predicting depressive disorders development. As the mediator of environmental risk factors, stress will function together with genetic and epigenetic mechanism to influence brain structure and function, physiology and psychology, and finally the vulnerability to depressive disorders.