Dynamic contrast-enhanced MRI reveals glymphatic dysfunction in mice with depressive-like behavior.

To investigate the behavioral changes and monoamine neurotransmitter levels in a rat model of chronic unpredictable mild stress (CUMS)-induced depression and explore the potential effects of Vitamin B12 (VitB12) on CUMS model rats and the underlying mechanisms. A total of 72 Sprague-Dawley (SD) rats were randomly assigned to 3 groups, a control group, a CUMS group (subjected to three weeks of CUMS), and a CUMS + VitB12 group (CUMS rats receiving microinjections of VitB12 in the neck). The body mass of the rats was measured, and behavioral assessments were conducted using the sucrose preference test, open field test, and forced swimming test. High-performance liquid chromatography (HPLC) was used to analyze the levels of monoamine neurotransmitters, including 5-hydroxytryptamine (5-HT), norepinephrine (NE), and dopamine (DA), in each group of rats. Hematoxylin-eosin (HE) staining was performed to observe pathological changes in hippocampal neurons. Western blot was performed to detect the expression of signal pathway-related proteins, including brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B (TrkB), and cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) in the hippocampal tissue. Starting from week 5, rats in the CUMS group exhibited lower average body mass compared to the control group, while the CUMS + VitB12 group showed a significant increase in body mass compared to the CUMS group (P < 0.05). At weeks 3 and 6, sucrose preference of rats in the CUMS group was significantly lower than that in the control group (P < 0.001). At week 3, sucrose consumption in the CUMS + VitB12 group was significantly higher than that in the CUMS group (P < 0.01), with a more pronounced increase observed in week 6 (P < 0.001). Starting from week 4, the CUMS group showed reduced scores in grid crossing, grooming, and rearing activities in the open field test compared to the control group, indicating reduced locomotor activity and exploratory behavior (P < 0.001). The CUMS + VitB12 group showed improved behavioral performance compared to the CUMS group (P < 0.01, P < 0.001). In the forced swimming test at weeks 3 and 6, the immobility time of rats in the CUMS group was significantly longer than that in the control group (P < 0.01). At week 6, the immobility time of rats in the CUMS + VitB12 group was significantly shorter compared to that of the CUMS group (P < 0.01). HPLC results showed that the levels of 5-HT, NE, and DA in the cerebral cortex of rats in the CUMS group were significantly lower than those in the control group (P < 0.01, P < 0.001), while these neurotransmitter levels were significantly higher in the CUMS + VitB12 group compared to those in the CUMS group (P < 0.05, P < 0.01). HE staining results showed that the number of hippocampal cells in the CUMS group was significantly reduced, with shrunken nuclei, while the CUMS + VitB12 group showed an increased number of neurons with intact morphology compared to the CUMS group (P < 0.05). Western blot analysis showed that the expression levels of BDNF, TrkB, and CREB proteins in the hippocampus were significantly lower in rats in the CUMS group than those in the control group (P < 0.05), while the expression levels of BDNF, TrkB, and phosphorylated CREB (p-CREB) were significantly higher in the CUMS + VitB12 group compared to the CUMS group (P < 0.05). In CUMS rats, the levels of monoamine neurotransmitters (5-HT, NE, and DA) in the cerebral cortex of the brain are decreased, accompanied by a decrease in neuronal cells, which results in anxiety- and depression-like behaviors. VitB12 can upregulate the levels of these neurotransmitters, ameliorate the cytopathological conditions, and regulate the BDNF/TrkB/p-CREB signaling pathway, thereby alleviating depressive symptoms.

Anti-inflammatory properties of brilliant blue G on chronic unpredictable mild stress-induced changes in rat hippocampus

PI3K-AKT-mTOR signaling pathway regulates autophagy of hippocampal neurons in diabetic rats with chronic unpredictable mild stress

Objective To investigate the effect of repetitive transcranial magnetic stimulation (rTMS) on the depressive like behaviors and expression of brain derived neurotrophic factor (BDNF), IL-1β and NF-κB of hippocampal in chronic unpredictable mild stress (CUMS) rats. Methods Thirty-two adult male rats were randomly divided into four groups (n=8): Control group, Control+ rTMS group, CUMS group and CUMS+ rTMS group. The sucrose preference test, forced swim test and open field test were used to evaluate depressive like behaviors for each groups. In addition, the expression of BDNF, NF-κB and IL-1β in hippo were detected by western blot and ELISA after behavioral test, respectively. Results 1.The effects of rTMS on depressive like behaviors of CUMS rats: in the sucrose preference test, the sucrose preference rate of CUMS rats (0.67±0.06) was significantly lower than Control group (0.91±0.04), which was higher in the CUMS+ rTMS group (0.83±0.08). In the forced swim test, the immobility time of CUMS group ((26.88±11.33)s) was longer than Control group ((15.22±6.75)s) and CUMS+ rTMS group ((18.41±6.95)s). In the open field test, both the total distance traveled and number of central area entry times of CUMS group((849.165±769.01)cm, (7.42±5.68)) were significantly shorter ((6224.81±1403.2)cm) and smaller (22.86±3.72) than Control group, and those of the CUMS+ rTMS were longer ((4105.57±1516.92)cm) and larger (21.25±3.45). All the behavioral results were statistically significant (P 0.05). 2. The effects of rTMS on the hippocampal expressions of BDNF, NF-κB and IL-1β in CUMS rats: compared with Control group, the hippocampal expression of BDNF in CUMS rats was significantly decreased, while the expressions of NF-κB and IL-1β in the hippocampus were significantly increased (P<0.05). Compared with CUMS group, the hippocampa expression of BDNF in the CUMS+ rTMS group was increased, and the expressions of NF-κB and IL-1β in the hippocampus was significantly decreased (P<0.05). There are no expressions of BDNF, NF-κB and IL-1β between Control group and Control+ rTMS group had no differences. Conclusion rTMS increased the expression of BDNF, reduced the production of NF-κB and IL-1β, and alleviated depressive like behaviors in CUMS rats. Key words: Repetitive transcranial magnetic stimulation; BDNF; NF-κB; IL-1β; Rats

Harmane suppresses microglial neuroinflammatory response and induce antidepressant-like effect in rats

Introduction: The prevalence of major depressive disorder (MDD) has gradually increased and has attracted widespread attention. The aim of this study was to investigate the effect of a probiotic compound consisting of Bacillus coagulans and Clostridium butyricum, on a mouse depression model.Methods: Mice were subjected to chronic unpredictable mild stress (CUMS) and then treated with the probiotics at different concentrations. And mice received behavior test such as forced swimming test and tail suspension test. After that, all mice were sacrificed and the samples were collected for analysis. Moreover, prefrontal cortex (PFC) gene expression and the gut microbiota among different groups were also analyzed.Results: Probiotics improved depressive-like behavior in CUMS mice, as indicated by decreased immobility time (p &amp;lt; 0.05) in the forced swimming test and tail suspension test. probiotics intervention also increased the level of 5-hydroxytryptamine (5-HT) in the prefrontal cortex and decreased the adrenocorticotropic hormone (ACTH) level in serum. In addition, by comparing the PFC gene expression among different groups, we found that the genes upregulated by probiotics were enriched in the PI3K-Akt signaling pathway in the prefrontal cortex. Moreover, we found that downregulated genes in prefrontal cortex of CUMS group such as Sfrp5 and Angpt2, which were correlated with depression, were reversed by the probiotics. Furthermore, the probiotics altered the structure of the gut microbiota, and reversed the reduction of cob(II)yrinate a,c-diamide biosynthesis I pathway in CUMS group. Several species like Bacteroides caecimuris and Parabacteroides distasoni, whose abundance was significantly decreased in the CUMS group but reversed after the probiotics intervention, showed significantly positive correlation with depression associated genes such as Tbxas1 and Cldn2.Discussion: These findings suggested that CUMS-induced depression-like behavior can be alleviated by the probiotics, possibly through alterations in the PFC gene expression and gut microbiota.

Current evidence supports the idea that neural plasticity is a potential cause of depression. Abundant studies indicate that CRMP2 has important roles in neural plasticity. Moreover, CRMP2 may contribute to the etiology of depression. However, the regulatory mechanisms underlying the role of CRMP2 remain unclear. DNA methylation alteration is generally acknowledged to be involved in the development of depression. The aim of this study was to explore the relationship between the expression and DNA methylation of CRMP2 in the hippocampus and prefrontal cortex of a rat depression model. Chronic unpredictable mild stress (CUMS) was used to establish a rat depression model, and body weight and behavioral tests were used to evaluate the effects of stress. Real-time PCR and Western blotting were used to test CRMP2 mRNA and protein expression, respectively, in the hippocampus and prefrontal cortex of rats. DNA methylation levels of the CRMP2 promoter were analyzed by bisulfite sequencing PCR (BSP). CUMS caused depressive-like behavior in rats, as evidenced by: decreased body weight and sucrose preference rate; decreases in the total distance traveled, rearing frequency, velocity, and duration in the center in the open field test (OFT); and prolonged immobility in the forced swimming test (FST). CRMP2 mRNA and protein expression in the hippocampus and prefrontal cortex were significantly decreased in the CUMS group compared with the control group. The levels of CRMP2 promoter DNA methylation in the hippocampus of the CUMS group were significantly higher than those of the control group, while these changes were not observed in the prefrontal cortex of CUMS rats. Our data provide evidence that altered expression of CRMP2 in the hippocampus and prefrontal cortex is associated with the pathogenesis of depression. Moreover, the results also suggest regional differences in the regulation of DNA methylation in the CRMP2 promoter between the hippocampus and prefrontal cortex during the development of depression.

Background:Depressive disorder is the leading cause of disability and suicidality worldwide. Metabolites are considered indicators and regulators of depression. However, the pathophysiology of the prefrontal cortex (PFC) in depression remains unclear.MethodsA chronic unpredictable mild stress (CUMS) model and a maturation rodent model of depression was used to investigate metabolic changes in the PFC. Eighteen male Sprague-Dawley rats were randomly divided into CUMS and control groups. The sucrose preference test (SPT) and forced swimming test (FST) were employed to evaluate and record depression-associated behaviors and changes in body weight (BW). High-performance liquid chromatography–tandem mass spectrometry was applied to test metabolites in rat PFC. Furthermore, principal component analysis and orthogonal partial least-squares discriminant analysis were employed to identify differentially abundant metabolites. Metabolic pathways were analyzed using MetaboAnalyst. Finally, a metabolite-protein interaction network was established to illustrate the function of differential metabolites.ResultsSPT and FST results confirmed successful establishment of the CUMS-induced depression-like behavior model in rats. Five metabolites, including 1-methylnicotinamide, 3-methylhistidine, acetylcholine, glycerophospho-N-palmitoyl ethanolamine, α-D-mannose 1-phosphate, were identified as potential biomarkers of depression. Four pathways changed in the CUMS group. Metabolite-protein interaction analysis revealed that 10 pathways play roles in the metabolism of depression.ConclusionFive potential biomarkers were identified in the PFC and metabolite-protein interactions associated with metabolic pathophysiological processes were explored using the CUMS model. The results of this study will assist physicians and scientists in discovering potential diagnostic markers and novel therapeutic targets for depression.

Simple SummaryDepression is a psychiatric disorder that represents a growing issue worldwide. This mental disorder is considered a mood disorder characterized by deep sadness and lethargy. A healthy diet is linked to enhanced mental health, whereas a bad diet is linked to an increased risk of depression and anxiety. Several studies have reported a positive association between vitamin D deficiency and depression. Therefore, we aimed to examine the effects of vitamin D3 (VD3) on a rat model of depression, which is induced by chronic unpredictable mild stress (CUMS). Behavioral tests were used to measure changes in depressive behaviors, as well as the levels of corticosterone and vitamin D in the blood. The groups that received doses of vitamin D produced better results than the group that did not receive any treatment in some behavioral tests. Vitamin D also had a protective role in preventing an increase of the corticosterone hormone, as well as an effective role in preventing a decrease in the level of vitamin D serum in the blood. The results of this research suggest that VD3 has a protective effect against anxiety and depression produced by CUMS in rats.Depression is a psychiatric disorder that negatively affects how a person feels, thinks, and acts. Several studies have reported a positive association between vitamin D (VD) deficiency and depression. Therefore, we aimed to examine the effects of intraperitoneal injection of VD3, fluoxetine (antidepressant), and a combination of VD3 + fluoxetine on a rat model of chronic unpredictable mild stress (CUMS). A total of 40 male Wistar rats (224–296 g) were divided into five groups (n = 8 each) as follows: (1) the control group, (2) the CUMS group, (3) the CUMS group that received vitamin D (10 μg/kg), (4) the CUMS group that received fluoxetine (5 mg/kg), and (5) the CUMS group that received both vitamin D (10 μg/kg) and fluoxetine (5 mg/kg). The CUMS model was produced by exposing rats to frequent social and physical stressors for 21 days. In addition, blood samples were collected to determine corticosterone and serum VD levels. Also, behavioral tests were conducted, including the sucrose preference test (SPT), the forced swimming test (FST), the tail suspension test (TST), the open field test (OFT), and the elevated plus maze test (EPM). Our results show that VD3 had effects similar to fluoxetine on the depressive behavior of the rats when measured by three behavioral tests, namely SPT, FST, and OFT (p < 0.001). Additionally, VD3 had a protective effect against depression similar to that of fluoxetine. Corticosterone levels were lower in the CUMS group that received vitamin D and the CUMS group that received both vitamin D and fluoxetine than in the CUMS group (p < 0.000). In conclusion, VD3 has a protective effect against anxiety and depressive behaviors produced by CUMS in rats.

Cang-ai volatile oil improves depressive-like behaviors and regulates DA and 5-HT metabolism in the brains of CUMS-induced rats

Objective To investigate the effect of chaihu-shugan-san (CSS) on the behaviors and Notch1 signal pathway in depression model rats. Methods Thirty-two SD rats with similar behavioral scores were divided into control group (CON), model group (CUMS), positive control group (FLU) and intervention group (CSS). The depression model was established by stimulating with chronic unpredictable mild stress (CUMS), and the behaviors evaluation was assessed by sugar water consumption and forced depression.Immunofluorescence was used to detect the proliferation of hippocampus neurons in rats, at the same time, real-time PCR and Western blot were used to detect the mRNA and protein expression levels of each factor (Notch1, Hes1, Hes5 and Jagged1) of Notch1 signal pathway respectively. Results Compared with CON group, the percentage of sugar water preference and swimming length of rats decreased significantly in CUMS group (P<0.05 and P<0.01). Compared with CUMS group, the percentage of sugar water preference and swimming length of rats increased significantly in CSS group(P<0.05). Compared with CON group, there was a significant increase in the inactivity length of rats between CUMS group, FLU group and CSS group, and the difference was statistically significant (P<0.01). Compared with CUMS group, the swimming length of rats in CSS group was significantly reduced, and the difference was statistically significant (P<0.01). Compared with CON group((750.00±27.51)/mm2), the number of BrdU positive cells in the substratum or granulocyte layer of the hippocampus dentate gyrus of rats in CUMS group ((338.75±29.61)/mm2), FLU group ((545.00±17.73)/mm2) and CSS group ((529.38±13.74)/mm2) was significantly reduced(P<0.01). Compared with CUMS group ((338.75±29.61)/mm2), there was a significant increase in the number of BrdU positive cells in the substratum or granulocyte layer of the hippocampus dentate gyrus of rats in CSS group ((529.38±13.74)/mm2), and the difference was statistically significant (P<0.01). Compared with CON group, the mRNA and protein expression levels of Notch1, Hes1, Hes5, and Jagged1 in the hippocampus of rats in CUMS group were significantly reduced(P<0.05 or P<0.01). Compared with CUMS group, the mRNA and protein expression levels of Notch1, Hes1, Hes5 and Jagged1 in the hippocampus of rats in FLU group and CSS group were significantly increased, and the differences were statistically significant (P<0.05 or P<0.01). Conclusion Notch1 signal pathway may be related to the obstacle during the hippocampus nerve regenerating in the model rat under chronic unpredictable mild stress.CSS may play an anti-depressant role by regulating Notchl to improve hippocampus nerve regeneration. Key words: Chaihu-shugan-san(CSS); Chronic unpredictable mild stress; Depression; Notch1 signal pathway

To detect the effects of metformin on the depressive-like behaviors in rats. Forty male SD rats were randomly divided into four groups: control group (CON group), metformin group (MET group), model group (CUMS group), model + metformin group (CUMS + MET group), 10 rats in each group. Chronic unpredictable mild stress (CUMS) method was used to establish rat depression model in three weeks. After the model was established successfully, two metformin groups were intraperitoneally injected with metformin (100 mg/kg), while the control group and the model group were injected with the same amount of saline once a day for two weeks. After that, the changes of weight gain, sucrose water preference experiment, forced swimming test, tail suspension immobility test and open field test were detected. The morphological changes of hippocampus were observed by Nissl staining. Compared with the control group, the weight gain of rats in CUMS group was significantly slowed down (P＜0.05), the sucrose preference rate and the spontaneous activity were significantly reduced (P＜0.05), and the immobility time in forced swimming and tail suspension immobility test was significantly prolonged (P＜0.05), and the morphological structure of hippocampus was changed, which confirmed the success of CUMS depression model. Compared with CUMS group, metformin treatment had no significant effect on body weight of rats, but it could significantly improve sucrose water intake, immobility time and spontaneous activity of CUMS depression model rats (P＜0.05), and improve the abnormal morphological changes of hippocampus in CUMS rats. Metformin has a therapeutic benefit against CUMS-induced depression, which provides a new treatment for patients with diabetes mellitus complicated with depression.

Chronic unpredictable mild stress-induced behavioral changes are coupled with dopaminergic hyperfunction and serotonergic hypofunction in mouse models of depression

Objective To investigate the expression levels of miRNA132 in patients with the first-episode major depressive disorder(MDD) and in chronic unpredictable mild stress(CUMS)rats.Methods Forty-one first-episode MDD patients(MDD group)were recruited from the outpatient departments of Hangzhou Seventh People's Hospital between March 2017 and May 2018,and 31 healthy volunteers(control group)were recruited.The patients' severity of symptoms was assessed with HAMD17.In addition,24 male SD rats were equally assigned into control group and CUMS group.The depression-like behaviors of rats was detected by sucrose preference test and forced swimming test.Plasma corticosterone levels of rats were assayed by ELISA.The expression levels of miRNA132 in the blood or prefrontal cortex were detected by quantitative real-time PCR.Results The expression level of miRNA132 in peripheral blood was significantly higher in MDD group(2.37±0.36)than in control group(1.34±0.16)(t=2.355,P=0.0213),and there was a positive correlation between miRNA132 levels and the HAMD17 score in MDD group(P=0.0004,rs=0.5303,n=41).The immobility time of CUMS group [(72.67±2.95)s] was significantly longer than that of control group [(40.00±5.49)s] in forced swim test(t=2.366,P=0.0395).The sucrose intake of CUMS group [(55.67±6.42)%] was significantly lower than that of control group [(98.21±1.28)%] in sucrose preference test(t=6.502,P<0.0001).The plasma corticosterone level in CUMS group [(1396.0±254.9)nmol/L] was significantly higher than that of control group [(557.3±158.4)nmol/L](t=2.795,P=0.0190).The miRNA132 levels in blood(2.32±0.88)and prefrontal cortex(2.80±0.76)of CUMS rats were significantly higher than those [1.18±0.36(t=2.273,P=0.0463)and 0.99±0.23(t=2.553,P=0.0287),respectively] of control group.Conclusions The expression trend of miRNA132 in peripheral blood is consistent between MDD patients and CUMS rats.In CUMS rats,the expression of miRNA132 in blood is also consistent with that in prefrontal cortex.The expression of miRNA132 in blood may reflect the change trend of miRNA132 expression in prefrontal cortex.

This study evaluated the antidepressant-like effect of lipid extract of C. striatus in chronic unpredictable mild stress (CUMS) model of depression in male rats and its mechanism of action. The animals were subjected to CUMS for six weeks by using variety of stressors. At the end of CUMS protocol, animals were subjected to forced swimming test (FST) and open field test followed by biochemical assay. The CUMS protocol produced depressive-like behavior in rats by decreasing the body weight, decreasing the sucrose preference, and increasing the duration of immobility in FST. The CUMS protocol increased plasma corticosterone and decreased hippocampal and prefrontal cortex levels of monoamines (serotonin, noradrenaline, and dopamine) and brain-derived neurotrophic factor. Further, the CUMS protocol increased interleukin-6 (in hippocampus and prefrontal cortex) and nuclear factor-kappa B (in prefrontal cortex but not in hippocampus). The lipid extract of C. striatus (125, 250, and 500 mg/kg) significantly (p < 0.05) reversed all the above parameters in rats subjected to CUMS, thus exhibiting antidepressant-like effect. The mechanism was found to be mediated through decrease in plasma corticosterone, increase in serotonin levels in prefrontal cortex, increase in dopamine and noradrenaline levels in hippocampus and prefrontal cortex, increase in BDNF in hippocampus and prefrontal cortex, and decrease in IL-6 and NF-κB in prefrontal cortex.