Antidepressant effects of Yuanzhi (Polygalae Radix) extract on chronic unpredictable mild stress-induced depression in rats: modulation of the NLRP3 inflammasome and NF-κB pathway

Objective To investigate the antidepressant effects of Yuanzhi(Polygalae Radix;PR)aqueous extract on chronic unpredictable mild stress(CUMS)-induced depression rat models and the underlying mechanisms.Methods A total of 40 male Sprague Dawley(SD)rats were randomly divided into control;model;low dose of PR(PR-L;0.5 g/kg);high dose of PR(PR-H;1 g/kg);and fluoxetine(10 mg/kg)groups;with 8 rats in each group.Except for the rats in control group;those in the other four groups underwent CUMS-induced depression modeling.PR and fluoxetine were administered intragastrically once daily;30 min prior to the CUMS procedure;for 14 consecu-tive days until the behavioral tests were performed.After CUMS modeling;the sucrose prefer-ence test(SPT);open field test(OFT);novelty-suppressed feeding test(NSFT);forced swim test(FST);and tail suspension test(TST)were employed to assess the pharmacological ef-fects of PR on the mitigation of depressive-like behaviors in rat models.Additionally;the en-zyme-linked immunosorbent assay(ELISA)was utilized to quantify the serum levels of tumor necrosis factor(TNF)-α;interleukin(IL)-6;and IL-1βin the rats.Western blot analysis was al-so conducted to evaluate the protein expression levels of nuclear factor kappa-B(NF-κB);in-ducible nitric oxide synthase(iNOS);cyclooxygenase-2(COX-2);nucleotide-binding oligomerization domain(NOD)-like receptor family pyrin domain containing 3(NLRP3);apoptosis-associated speck-like protein containing caspase recruitment domain(ASC);and caspase-1 in the hippocampal tissues of the rats.Immunofluorescence staining was per-formed to observe the morphological changes in ionized calcium-binding adapter molecule 1 positive(Iba-1+)cells in the dentate gyrus(DG)of rats with CUMS-induced depression.Results(i)Treatment with PR-H and fluoxetine resulted in significant enhancements in both the total distance and time the rats moved during tests(P<0.01 and P<0.05;respectively).Post-administration of PR-H and fluoxetine also led to statistically significant increase in su-crose preference among rats(P<0.05).Besides;PR-L;PR-H;and fluoxetine treatment markedly decreased the latency of ingestion(P<0.05;P<0.05;and P<0.01;respectively).As observed from the FST;PR-L;PR-H;and fluoxetine presented antidepressant effects on rats with CUMS-induced depression;leading to the reduction in time of their immobility(P<0.05;P<0.01;and P<0.01;respectively).The results of TST indicated reduced immobility time in rats receiving PR-H and fluoxetine treatment as well(P<0.01).(ii)Rats in model group showed an increase in the levels of Iba-1+microglia in their left and right brains in compari-son with control group(P<0.01).However;such increase was negated post PR treatment(P<0.01).Treatment with PR-L;PR-H;and fluoxetine considerably reduced the levels of inflam-matory factors(TNF-α;IL-1β;and IL-6;P<0.01).In addition;treatment of PR-L and PR-H ef-fectively counteracted the elevated levels of NLRP3;ASC;and caspase-1;and markedly down-regulated the expression levels of phosphorylated p65(p-p65);COX-2;and iNOS in rats’hip-pocampus(P<0.01).Conclusion Collectively;these findings indicate that PR exerts an antidepressant effect on rats with CUMS-induced depression partially through the modulation of the NLRP3 and NF-κB signaling pathways.

Shuganheweitang Ameliorates Chronic Unpredictable Mild Stress-Induced Depression-Like Behaviors in Rats through the PI3K/AKT/mTOR Pathway: Involvement of Amino Acids, Glycerophospholipids, and Energy Metabolism

Background: Depression is a typical psychosomatic disease. Shuganheweitang (SGHWT) is a clinical formula that effectively treats depression. However, the potential mechanism used by SGHWT to ameliorate depression-like behaviors is still unclear. This study investigated the effects of SGHWT on metabolic change in the liver and hypothalamus with signaling pathways involved in chronic unpredictable mild stress (CUMS)-induced depression in rats to explore the mechanism of the anti-depressive effect. Methods: A total of 52 rats were used to create a model of depression by CUMS combined with solitary rearing for 6 weeks. Open field test (OFT), sucrose preference test (SPT), forced swim test (FST), and body weight (BW) were performed to analyze the pharmacodynamic effects of SGHWT. H&E staining, Nissl staining, immunofluorescence, immunohistochemistry, and western blot were used to evaluate the mechanism of action. Untargeted metabolomics techniques by ultra-performance liquid chromatography-quantitative time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) were used to analyze all the metabolic differences in the liver and hypothalamus. Results: SGHWT improved CUMS-induced depression-like behaviors in vivo. SGHWT reduced hepatic c-Fos protein expression and increased hypothalamic c-Fos protein expression. Moreover, p-PI3K, p-AKT473, p-AKT308, and p-mTOR protein expressions were significantly downregulated in the liver and hypothalamus of CUMS rats. Notably, these alterations were reversed by the SGHWT administration. Furthermore, the metabolomic analysis identified 15 and 5 key differential SPT-associated metabolites in the liver and hypothalamus, respectively. Conclusion: This study suggests that SGHWT ameliorates chronic unpredictable mild stress-induced depression-like behaviors, by the involvement of amino acids, glycerophospholipids, energy metabolism, and the PI3K/AKT/mTOR pathway. Highlights: 1) Shuganheweitang was derived from the TCM herbal formula Sinisan. 2) SGHWT treatment reverses depression-like behaviors in CUMS-induced rats. 3) The mechanism of SGHWT on depression by the liver and hypothalamus metabolomics. 4) SGHWT regulates amino acids, glycerophospholipids, and energy metabolism. 5) SGHWT exerts antidepressant effects through the PI3K/AKT/mTOR pathway.

Glutamate Transporter 1-mediated Antidepressant-like Effect in a Rat Model of Chronic Unpredictable Stress

In recent years, more attention has been paid to the role of the glutamate transporter 1 （GLT-1, EAAT2） in major depressive disorder （MDD）. However, experimental data on brain GLT-1 levels are, to some extent, inconsistent in human postmortem and animal studies, These discrepancies imply that the role of GLT-1 in the pathophysiology of MDD and the action of antidepressants remain obscure. This work was designed to study the impact of chronic unpredictable stress （CUS） for 2 ses- sions per day for 35 days and four weeks of fluoxetine （FLX） on depressive-like behaviors in rats, as well as the concomitant expression of the GLT-1 protein in the hippocampus. Behavioral changes were assessed by the sucrose preference and open field tests. GLT-1 levels were detected by immunohisto- chemistry and Western blot analysis. Our study demonstrated that the animals exposed to CUS showed depressive-like behaviors and exhibited a significant decrease in GLT-1 expression in the hippocampus. Chronic FLX treatment reversed the behavioral deficits and the CUS-induced decrease in GLT-1 levels. Taken together, our results support the reduction of GLT-1 in human postmortem studies in MDD and suggest that GLT-1 may be involved in the antidepressant activity of FLX. Our studies further support the notion that GLT-1 is an attractive candidate molecule associated with the fundamental processes of MDD and may be a potential, and novel pharmacological target for the treatment of MDD.

Jobelyn^(■), a Sorghum-Based Nutritional Supplement Attenuates Unpredictable Chronic Mild Stress-Induced Memory Deficits in Mice

The ability of an organism to adapt to aversive stressful situations or life challenging circumstances is very crucial to its state of health and survival. However, breakdown in adaptation due to persistent uncontrollable stress, leads to impairment of bodily functions and onset of a variety of pathological disorders especially memory decline. This study was designed to evaluate the effect of Jobelyn&reg;(JB), a potent antioxidant sorghum-based food supplement on unpredictable chronic mild stress (UCMS)-induced memory impairment in mice. Male Swiss mice were given JB (5 - 50 mg/kg, p.o) 30 min prior to exposure to UCMS for 14 consecutive days before testing for memory. Thereafter, the serum corticosterone level was estimated by using ELISA kits. The levels of malondialdehyde (MDA) and glutathione (GSH) as well as acetylcholinesterase activity were estimated in the brain homogenate using spectrophotometer. Histology of the brain tissues and estimation of the populations of viable neurons in the hippocampal region were done after staining with hematoxyline and eosin. Our results showed that JB reversed memory impairment and suppressed corticosterone concentrations induced by UCMS. Moreover, JB reduced oxidative stress in the brain of UCMS-mice as shown by decreased MDA levels and elevated GSH concentrations. It also decreased brain acetylcholinesterase activity when compared with chronic stress group (p < 0.05). Furthermore, JB (5 - 10 mg/kg, p.o) offered significant protection against UCMS-induced degeneration and death of neuronal cells of the cornu ammonis 3 (CA3) of the hippocampal region of the brain indicating neuroprotection. Taken together, these findings suggest that JB attenuates memory deficits induced by UCMS in mice and may be useful therapeutically for stress-related cognitive dysfunctions. The reduction in the levels of serum corticosterone, antioxidation, neuroprotection and inhibition of cholinesterase enzyme might be contributing significantly to the positive effect of JB on memory in mice exposed to unpredictable chronic mild stress.

Citrus aurantium L. extract alleviate depression by inhibiting gut microbiota-mediated inflammation in mice

Gut microbiota plays a crucial role in the pathophysiology of depression.This study aimed to explore the antidepressant effect of mature whole Citrus aurantium fruit extract(FEMC)in the chronic unpredictable mild stress(CUMS)model.The behavioral tests were applied to assess antidepressant effect and 16S rRNA sequencing was used to analyze the changes of gut microbiota.The results showed that the major components of FEMC were naringin and neohesperidin and significantly increased the sucrose preference index of the mice.FEMC also could reduce the feeding latency in an open field test and the rest time in a novelty suppressed feeding test.In addition,FEMC could increase CUMS-induced reduction in the levels of BDNF,PSD95,and SYN in the hippocampus.Moreover,FEMC intervention slightly decreased the ratio of Firmicutes to Bacteroidota.Meanwhile,FEMC reduced the abundance of the Prevotellaceae_Ga6A1_group,[Ruminococcus]_torques_group,which have been reported to be closely related to inflammation.Bioinformatics analysis revealed that mitogen-activated protein kinase(MAPK)signaling pathway and lipopolysaccharide biosynthesis were involved in the anti-inflammatory effect of FEMC in the CUMS animal model.Finally,the ELISA results showed that FEMC could significantly reduce the expression of pro-inflammatory cytokines IL-6 and TNF-αin the serum of depressive mice.Our results suggest FEMC can am eliorate depressive behavior by i nhibiting gut microbiota-mediated inflammation in mice.

LncRNA NPTN-IT1-201 Ameliorates Depressive-like Behavior by Targeting miR-142-5p and Regulating Inflammation and Apoptosis via BDNF

Objective Long noncoding RNAs(lncRNAs)and microRNAs(miRNAs)are widely expressed in the brain and are associated with the development of neurological and neurodegenerative diseases.However,their roles and molecular mechanisms in major depressive disorder(MDD)remain largely unknown.This study aimed to identify lncRNAs and miRNAs involved in the development of MDD and elucidate their molecular mechanisms.Methods Transcriptome and bioinformatic analyses were performed to identify miRNAs and lncRNAs related to MDD.C57 mice were subjected to chronic unpredictable mild stress(CUMS)to establish a depression model.Lentiviruses containing either lncRNA NPTN-IT1-201 or miR-142-5p were microinjected into the hippocampal region of these mice.Behavioral tests including the sucrose preference test(SPT),tail suspension test(TST),and forced swim test(FST)were conducted to evaluate depressive-like behaviors.Results The results revealed that overexpression of lncRNA NPTN-IT1-201 or inhibition of miR-142-5p significantly ameliorated depressive-like behaviors in CUMS-treated mice.Dual-luciferase reporter assays confirmed interactions between miR-142-5p with both brain-derived neurotrophic factor(BDNF)and NPTN-IT1-201.ELISA analysis revealed significant alterations in relevant biomarkers in the blood samples of MDD patients compared to healthy controls.Histological analyses,including HE and Nissl staining,showed marked structural changes in brain tissues following CUMS treatment,which were partially reversed by lncRNA NPTN-IT1-201 overexpression or miR-142-5p inhibition.Immunofluorescence imaging demonstrated significant differences in the levels of BAX,Bcl2,p65,Iba1 among different treatment groups.TUNEL assays confirmed reduced apoptosis in brain tissues following these interventions.Western blotting showed the significant differences in BDNF,BAX,and Bcl2 protein levels among different treatment groups.Conclusion NPTN-IT1-201 regulates inflammation and apoptosis in MDD by targeting BDNF via miR-142-5p,making it a potential therapeutic target for MDD.

Quercetin regulates depression-like behavior in CUMS rat models via TLR4/NF-κB signaling

Background:Depression is becoming increasingly prevalent around the world,imposing a substantial burden on individuals,families,as well as society.Quercetin is known to be highly effective in treating depression.However,additional research is needed to dissect the mechanisms of its anti-depressive effects.Methods:For this study,Sprague-Dawley(SD)rats were randomized into the control,model,quercetin,or fluoxetine group.The latter three groups were exposed to chronic unpredictable mild stress(CUMS)for 42 d.The first two groups received saline solution daily via oral gavage.Meanwhile,the quercetin group was orally administered a quercetin suspension(52.08 mg/kg)every day,while the fluoxetine group was orally administered a fluoxetine solution(2.08 mg/kg).Here,fluoxetine served as the positive control drug to compare the therapeutic effects of quercetin.The experimental period was 6 weeks.Depressive behaviors in rats were assessed through various physiological and behavioral measures.Additionally,pathological changes in hippocampal tissues were examined using Nissl staining.Serum cytokines were detected using an enzymelinked immunosorbent assay(ELISA),and immunohistochemistry was employed to quantify the levels and integral optical density(IOD)values of ionized calcium binding adaptor molecule-1(Iba-1)expression in the brain.Real-time fluorescence quantitative PCR(RT-qPCR)was utilized to evaluate the mRNA levels of inflammatory indicators as well as toll-like receptor 4(TLR4),and nuclear factor-κappa B P65(NF-κB P65)in hippocampus.Western blot(WB)technique was employed to observe the protein levels of TLR4,NF-κB P65,and phospho-NF-κB P65(p-NF-κB P65).Results:After 42 d of exposure to CUMS,rats exhibited a slow increase in body weight,a reduction in food intake,an abnormal preference for sugar water,and aberrant open-field behaviors.Pathological analysis revealed the disintegration,rupture,interruption,and disorganization of hippocampal neuronal cells after CUMS exposure,along with a decrease in Nissl bodies in the CA1 region.This was accompanied by the elevated expression of interleukin-1β(IL-1β),tumor necrosis factor-α(TNF-α),and interleukin-6(IL-6)in the serum and the upregulation of IL-1β,IL-6,and TNF-αmRNA expression in the hippocampus.Increases in Iba-1-positive cells and the IOD values of Iba-1 were detected in hippocampal microglia.Furthermore,TLR4 and NF-κB P65 mRNA and protein levels were upregulated in hippocampal tissues.Quercetin,an antidepressant,could alleviate depression-like symptoms in rats and downregulate inflammatory factors associated with the TLR4/NF-κB signaling pathway in hippocampal microglia,and its therapeutic effect was comparable to fluoxetine.Conclusion:In rat models of CUMS,quercetin may act as an antidepressant by inhibiting inflammation in hippocampal microglia via TLR4/NF-κB signaling pathway.These results offer experimental and theoretical support for applying quercetin in the clinical management of depression.

L-tyrosine improves neuroendocrine function in a mouse model of chronic stress

Adult BALB/c mice, individually housed, were stimulated with nine different stressors, arranged randomly, for 4 continuous weeks to generate an animal model of chronic stress. In chronically stressed mice, spontaneous locomotor activity was significantly decreased, escape latency in the Morris water maze test was prolonged, serum levels of total thyrotropin and total triiodothyronine were significantly decreased, and dopamine and norepinephrine content in the pallium, hippocampus and hypothalamus were significantly reduced. All of these changes were suppressed, to varying degrees, by L-tyrosine supplementation. These findings indicate that the neuroendocrine network plays an important role in chronic stress, and that L-tyrosine supplementation has therapeutic effects.

Integration of animal behaviors under stresses with different time courses

We used animal models of ＂forced swim stress＂ and ＂chronic unpredictable stress＂, and tried to reveal whether a passive coping style of high flotation behavior in forced swim stress predicts an- hedonia behavior after chronic unpredictable stress, and whether the dopamine system regulates floating and anhedonia behaviors. Our results confirmed that depression-prone rats use ＂floating behavior＂ as a coping strategy in forced swim stress and more readily suffer from anhedonia during chronic unpredictable stress. Intraperitoneal injection or nucleus accumbens microin- jection of the dopamine 2/3 receptor subtype agonist ropinirole reduced floating behaviors in depression-prone animals, but increased sucrose preference in rats showing anhedonia. These data indicate that floating behavior is a defensive mode that is preferred by susceptible individ- uals under conditions of acute stress. Simultaneously, these animals more readily experienced anhedonia under long-term stress; that is, they were more readily affected by depression. Our results suggest that dopamine 2/3 receptor subtypes in the nucleus accumbens play an important role in floating behaviors and anhedonia.

Vitamin D_(3) attenuates anxiety-like behavior in long-term ovariectomized rats with unpredictable mild stress

The impact of various vitamin D3(VD3)doses(1.0,2.5,or 5 mg/kg,s.c.)in mitigating the negative consequences of chronic unpredictable mild stress(CUMS)was investigated.Adult female rats with long-term estrogen deficiency were assessed using the sucrose preference test(SPT),the elevated plus-maze(EPM),the light/dark test(LDT),and the open-field test(OFT)to measure anhedonia-like and anxiety-like behavior.The corticosterone(CS)and adrenocorticotrophic hormone(ACTH)concentrations in blood serum and the brain-derived neurotrophic factor(BDNF)expression in the hippocampus of long-term ovariectomized(OVX)rats were measured by ELISA kits and/or western blotting.Treatment with VD3(5.0 mg/kg),similarly to fluoxetine(10.0 mg/kg),significantly reduced the anhedonia profile in the SPT and anxiety-like behavior in the EPM and LDT,and CS and ACTH levels in blood serum.It also elevated BDNF levels in the hippocampus of long-term OVX/CUMS compared to OVX/CUMS/solvent rats.Thus,these findings suggest that VD3(5.0 mg/kg)administration might attenuate the anxiety-like profile in long-term OVX adult rats subjected to the CUMS.This might occur via activation of the BDNF signaling pathway in the hippocampus and via restoration of CS and ACTH levels in blood serum.

Splenectomy does not affect mouse behaviors

The spleen is critical for immunity.It is the largest immune organ and immune center in the peripheral system.While the relationship between behavior and immunity has been demonstrated in physiology and diseases,the role of the spleen in behavior is not clear.To investigate the effects of the spleen on behaviors,we performed a refined splenectomy procedure on C57BL/6J mice and performed an open field test,circadian rhythm test,elevated plus maze,sucrose preference test,and Barnes maze test.Splenectomy did not induce changes in general locomotion,circadian rhythms,learning and memory,or depression/anxiety-related behaviors.To further investigate the effects of spleen on stress susceptibility,we established mouse models of depression through chronic unpredictable mild stress.The behavioral performances of mice subjected to splenectomy showed no differences from control animals.These findings suggest that splenectomy does not cause changes in baseline behavioral performance in mice.

Fluoxetine Ameliorates the Aggravation of UC Symptoms in C57BL/6 Mice Induced by CUMS

Objective Patients with chronic ulcerative colitis(UC)often have mental symptoms such as depression and anxiety,and stress can lead to gastrointestinal diseases.However,the correlation between mental stress and UC is unclear.In this paper,chronic unpredictable mild stress(CUMS)was utilized to evaluate the involvement of mental factors in the pathogenesis of UC.Methods The CUMS model was used to evaluate the direct/indirect involvement of mental factors in the pathogenesis of UC.The behavior was evaluated by the open field,forced swimming,and tail suspension tests.Body weight,the disease activity index(DAI)score,colon length,and HE staining of colon tissue were used to evaluate the action of CUMS and fluoxetine.Results The results showed that weight loss and the DAI score increased in CUMS mice,but they had no meaningful effect on colon length and morphological structure of colon tissue.However,CUMS aggravated dextran sulfate sodium(DSS)-induced colon length shortening and colon morphological structure damage.Fluoxetine significantly improved the DAI score,shortened colon length,and damaged morphology and structure of the colons induced by CUMS combined with DSS in mice.Fluoxetine also decreased the level of IL-6 in the serum and the TNF-αand IFN-γlevels of colon tissue.Fluoxetine simultaneously improved behavioral abnormalities induced by CUMS combined with DSS in mice.Conclusion CUMS aggravated the UC symptoms induced by DSS,and fluoxetine could improve the UC symptoms due to its improvement in the inflammatory level and behavioral abnormalities.

Effects of CUMS combined with CRS on hippocampal glial cells and synaptic plasticity in depressed mice

Objective:To explore the effects of CUMS combined with CRS on mouse hippocampal glial cells and synaptic plasticity-related proteins. Methods: Forty mice were randomly divided into normal group (n=20) and model group (n=20). The model group used CUMS combined with CRS to prepare a mouse model of depression for 7 weeks. The behavioral evaluation of the mice at 3 weeks and 7 weeks after modeling was performed by sugar water preference test, open field test and tail suspension test. After the experiment, the samples were collected, and the content of TNF-a in the hippocampus of mice was detected by enzyme-linked immunosorbent assay. Immunohistochemical method was used to detect the Iba-1 and GFAP MOD values of mouse hippocampal CA1 area, CA3 area and DG area. Western blot was used to detect the protein expression of Iba-1, GFAP, SYN1 and PSD-95 in the hippocampus. fluorescence quantitative PCR method was used to detect the expression of SYN1, PSD-95 mRNA in hippocampus. Results: At the 3rd week after modeling, the body weight, sugar water preference rate, total distance moved, number of standing uprights, and stay time in the central area of the mice in the model group were all lower than those in the normal group (P<0.05), and the tail suspension immobility time was longer than that in the normal group (P<0.01). After 7 weeks of modeling, the body weight, sugar water preference rate, total distance moved, number of erection times, central area residence time, and average movement speed of the mice in the model group were lower than those in the normal group (P< 0.05), the tail suspension immobility time was longer than that in the normal group (P<0.01). The contents of TNF-a in the hippocampus were higher than those in the normal group (P<0.05). The GFAP MOD value and the relative expression of GFAP protein in hippocampal CA1, CA3 and DG regions were significantly lower than those in the normal group (P<0.05). The Iba-1 MOD value and the relative expression of Iba-1 protein in hippocampal CA1, CA3 and DG regions were significantly higher than those in the normal group (P<0.05). The relative expression of SYN1 and PSD-95 protein and the relative expression of SYN1 and PSD-95 mRNA in the hippocampus were significantly lower than those in the normal group (P<0.05). Conclusion: After 3 weeks of CUMS and CRS modeling, the depression-like behavior of mice appeared, and the depression of mice was more obvious after 7 weeks of modeling. The depression mouse model made by CUMS combined with CRS method may be related to increased hippocampal inflammation, excessive activation of microglia, decreased number of astrocytes and decreased synaptic plasticity.

Increased expression level of corticotropin-releasing hormone in the amygdala and in the hypothalamus in rats exposed to chronic unpredictable mild stress

Objective Corticotropin-releasing hormone（CRH）plays an important role in neuroendocrine,autonomic and behavioral responses to stressors.In the present study,the effect of chronic unpredictable mild stress（CUMS）on CRH neurons was investigated in rat brain.Methods The rats were exposed to one of the stressors each day for 21 d.Immunostaining was performed to detect the CRH-positive neurons in the paraventricular nucleus（PVN）of the hypothalamus and in amygdala.Results After the stress protocol,the animals showed a reduction in body weight gain as well as reduced sucrose preference and locomotor activity.Interestingly,the CRH neurons in both PVN and central nucleus of the amygdala（CeA）were stimulated by CUMS.The densities of CRH-containing neurons in both PVN and CeA were significantly higher than those in control group.Conclusion The CRH systems in PVN and CeA may both contribute to depression-like behaviors during CUMS.

Antidepressant-like effect of essential oil of Perilla frutescens in a chronic, unpredictable, mild stress-induced depression model mice

Perilla frutescens(Perilla leaf), a garnishing vegetable in East Asian countries, as well as a plant-based medicine, has been used for centuries to treat various conditions, including depression. Several studies have demonstrated that the essential oil of P. frutescens(EOPF) attenuated the depressive-like behavior in mice. The present study was designed to test the anti-depressant effects of EOPF and the possible mechanisms in an chronic, unpredictable, mild stress(CUMS)-induced mouse model. With the exposure to stressor once daily for five consecutive weeks, EOPF(3, 6, and 9 mg·kg-1) and a positive control drug fluoxetine(20 mg·kg-1) were administered through gastric intubation to mice once daily for three consecutive weeks from the 3rd week. Open-field test, sucrose consumption test, tail suspension test(TST), and forced swimming test(FST) were used to evaluate the behavioral activity. The contents of 5-hydroxytryptamine(5-HT) and its metabolite, 5-hydroxyindoleacetic acid(5-HIAA), in mouse hippocampus were determined by HPLC–ECD. Serum interleukin(IL)-1, IL-6, and tumor necrosis factor(TNF)-α levels were evaluated by enzyme-linked immunosorbent assay(ELISA). The results showed that CUMS significantly decreased the levels of 5-HT and 5-HIAA in the hippocampus, with an increase in plasma IL-6, IL-1β, and TNF-α levels. CUMS also reduced open-field activity, sucrose consumption, as well as increased immobility duration in FST and TST. EOPF administration could effectively reverse the alterations in the concentrations of 5-HT and 5-HIAA; reduce the IL-6, IL-1β, and TNF-α levels. Moreover, EOPF could effectively reverse alterations in immobility duration, sucrose consumption, and open-field activity. However, the effect was not dose-dependent. In conclusion, EOPF administration exhibited significant antidepressant-like effects in mice with CUMS-induced depression. The antidepressant activity of EOPF might be related to the relation between alteration of serotonergic responses and anti-inflammatory effects.

Overexpression of brain-derived neurotrophic factor in the hippocampus protects against post-stroke depression

Post-stroke depression is associated with reduced expression of brain-derived neurotrophic factor （BDNF）. In this study, we evaluated whether BDNF overexpression affects depression-like behavior in a rat model of post-stroke depression. The middle cerebral artery was occluded to produce a model of focal cerebral ischemia. These rats were then subjected to isolation-housing combined with chronic unpredictable mild stress to generate a model of post-stroke depression. A BDNF gene lentiviral vector was injected into the hippocampus. At 7 days after injection, western blot assay and real-time quantitative PCR revealed that BDNF expression in the hippo- campus was increased in depressive rats injected with BDNF lentivirus compared with depressive rats injected with control vector. Furthermore, sucrose solution consumption was higher, and horizontal and vertical movement scores were increased in the open field test in these rats as well. These findings suggest that BDNF overexpression in the hippocampus of post-stroke depressive rats alleviates depression-like behaviors.

Antidepressant-Like Effects of Chaihu Shugan Powder(柴胡疏肝散)on Rats Exposed to Chronic Unpredictable Mild Stress through Inhibition of Endoplasmic Reticulum Stress-Induced Apoptosis

Objective:To investigate the antidepressant-like effects of Chaihu Shugan Powder(CSP,柴胡疏肝散)and to explore its underlying mechanisms.Methods:Thirty-two Sprague-Dawley rats were randomly divided into control(CON),chronic unpredictable mild stress(CUMS),fluoxetine(FLU),and CSP groups,8 rats in each group.All of the rats except for those in the control group were subjected to 3 consecutive weeks of CUMS to establish the depression model.The open field test(OFT),forced swimming test(FST),and sucrose preference test were used to assess the anti-anxiety and antidepressant effects of CSP.Terminal deoxynucleotidyl transferase(Td T)d UTP nick-end labeling was used to determine the apoptosis rate in the hippocampal tissues.The m RNA and protein levels of glucose-regulated protein(GRP)78,spliced X-box-binding protein(XBP)-1,CCAAT/enhancerbinding protein homologous protein(CHOP),caspase-12,and c-Jun N-terminal kinase(JNK)in the hippocampus of rats were evaluated by real-time PCR and Western blot analysis,respectively.Results:Administration of CSP alleviated anxiety and depression-like behavior in CUMS rats,as revealed by enhanced time and distance in the center of the OFT(P<0.05),an increased preference for sucrose,and longer swimming time and shorter immobility time during the FST(all P<0.05).In addition,CSP treatment significantly reduced the rate of apoptosis in rat hippocampal neurons(P<0.05).The m RNA and protein expression levels of GRP78,spliced XBP-1,and CHOP were down-regulated along with the expression of caspase-12 and cleaved caspase-12 proteins(all P<0.05),whereas total and phosphorylated JNK1 protein levels did not differ significantly between control and CSP-treated rats.Conclusion:CSP can improve depression-like behavior in rats exposed to CUMS,possibly by suppressing CHOP and caspase-12 mediated apoptosis in the rat hippocampus.

Shuganjieyu capsule increases neurotrophic factor expression in a rat model of depression

Shuganjieyu capsule has been approved for clinical treatment by the State Food and Drug Ad-ministration of China since 2008. In the clinic, Shuganjieyu capsule is often used to treat mild to moderate depression. In the rat model of depression established in this study, Shuganjieyu capsule was administered intragastrically daily before stress. Behavioral results conifrmed that depressive symptoms lessened after treatment with high-dose （150 mg/kg） Shuganjieyu capsule. Immunohistochemistry results showed that high-dose Shuganjieyu capsule signiifcantly increased phosphorylation levels of phosphorylation cyclic adenosine monophosphate response element binding protein and brain-derived neurotrophic factor expression in the medial prefrontal cortex and hippocampal CA3 area. Overall, our results suggest that in rats, Shuganjieyu capsule effec-tively reverses depressive-like behaviors by increasing expression levels of neurotrophic factors in the brain.

Exploration of the mechanism by which icariin modulates hippocampal neurogenesis in a rat model of depression

Icariin(ICA) has a significant capacity to protect against depression and hippocampal injury,but it cannot effectively cross the bloodbrain barrier and accumulate in the brain.Therefore,the mechanism by which ICA protects against hippocampal injury in depression remains unclear.In this study,we performed proteomics analysis of cerebrospinal fluid to investigate the mechanism by which ICA prevents dysfunctional hippocampal neurogenesis in depression.A rat model of depression was established through exposure to chronic unpredictable mild stress for 6 weeks,after which 120 mg/kg ICA was administered subcutaneously every day.The results showed that ICA alleviated depressive symptoms,learning and memory dysfunction,dysfunctional neurogenesis,and neuronal loss in the dentate gyrus of rats with depression.Neural stem cells from rat embryonic hippocampi were cultured in media containing 20% cerebrospinal fluid from each group of rats and then treated with 100 μM corticosterone.The addition of cerebrospinal fluid from rats treated with ICA largely prevented the corticosterone-mediated inhibition of neuronal proliferation and differentiation.Fifty-two differentially expressed proteins regulated by chronic unpredictable mild stress and ICA were identified through proteomics analysis of cerebrospinal fluid.These proteins were mainly involved in the ribosome,PI3 K-Akt signaling,and interleukin-17 signaling pathways.Parallel reaction monitoring mass spectrometry showed that Rps4 x,Rps12,Rps14,Rps19,Hsp90 b1,and Hsp90 aa1 were up-regulated by chronic unpredictable mild stress and down-regulated by ICA.In contrast,Htr A1 was down-regulated by chronic unpredictable mild stress and up-regulated by ICA.These findings suggest that ICA can prevent depression and dysfunctional hippocampal neurogenesis through regulating the expression of certain proteins found in the cerebrospinal fluid.The study was approved by the Experimental Animal Ethics Committee of Guangzhou University of Chinese Medicine of China in March 2017.

Fluoxetine ameliorates depressive symptoms by regulating lncRNA expression in the mouse hippocampus

Depression is a prevalent mental disorder that is associated with aging and contributes to increased mortality and morbidity.The overall prevalence of geriatric depression with clinically significant symptoms is currently on the rise.Recent studies have demonstrated that altered expressions of long non-coding RNAs(lncRNAs)in the brain affect neurodevelopment and manifest modulating functions during the depression.However,most lncRNAs have not yet been studied.Herein,we analyzed the transcriptome of dysregulated lncRNAs to reveal their expressions in a mouse model exhibiting depressive-like behaviors,as well as their corresponding response following antidepressant fluoxetine treatment.A chronic unpredictable mild stress(CUMS)mouse model was applied.A sixweek fluoxetine intervention in CUMS-induced mice attenuated depressive-like behaviors.In addition,differential expression analysis of lncRNAs was performed following RNA-sequencing.A total of 282 lncRNAs(134 up-regulated and 148 down-regulated)were differentially expressed in CUMS-induced mice relative to non-stressed counterparts(P<0.05).Moreover,370 differentially expressed lncRNAs were identified in CUMS-induced mice after fluoxetine intervention.Gene Ontology(GO)analyses showed an association between significantly dysregulated lncRNAs and protein binding,oxygen binding,and transport activity,while the Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis indicated that these dysregulated lncRNAs might be involved in inflammatory response pathways.Fluoxetine effectively ameliorated the symptoms of depression in CUMS-induced mice by regulating the expression of lncRNAs in the hippocampus.The findings herein provide valuable insights into the potential mechanism underlying depression in elderly people.