Brazilin Produces Antidepressant-like Effects In A Chronic Mild Stress Mice Model

Objective: Depression has become a serious public health and social problem,since its increasing incidence and disability.Increasing oxidative stress injury occur in the related brain regions,anti-oxidative stress drugs may could reverse the depressive-like behavior of depressed individuals,indicating that oxidative stress maybe a main contributor to the development of depression.Antidepressant drug development based on the “dysfunction of neuronal-endocrine-immune system” pathological mechanism of depression have attracted more and more attention.Natural products have attracted increasing attention in preventing and treating neurodegenerative and psychiatric disorders,including depression.Many types of natural products have the considerable effect with fewer side effects compared with prescription medications.Brazilin,a major constituent of the traditional Chinese herbal plant Caesalpinia sappan L,has been reported to possess various biological activities,including anti-inflammatory,anticancer and immuno-regulatory activities.However,its potential antidepressant-like effect are still elusive.Considering its anti-inflammatory and immunomodulatory activities,we hypothesized that brazilin may have neuroprotective and antidepressant-like effects.Also,H₂O₂ is one of the main components of free radical activity in cells,exogenous H₂O₂ is often used as a inducer of oxidative damage to investigate the mechanism of cell injuries induced by oxidative stress and preliminarily screen of potential protective drugs in vitro.Based on the correlation connection between depression and oxidative stress injuries,we use the H₂O₂-induced oxidative stress cell injuries paradigm and the chronic mild stress?CMS?mice depression model in vivo and in vitro.The present study aimed to investigate the potential effects of brazilin on oxidative stress-induced PC12 cell injuries and CMS-induced depressive-and anxiety-like behaviors.Methods: 1 Effects of brazilin on H₂O₂-induced cell injury in vitro.1.1 Establishment of H₂O₂-induced PC12 cell model.1.2 Effects of brazilin or H₂O₂ treatment on PC12 cell survival assessed by MTS analysis.1.3 Effects of brazilin on H₂O₂-induced cellular injuries detected by MTS assay.1.4 Effects of brazilin on H₂O₂-induced PC12 cell apoptosis and necrosis assessed by Annexin V-FITC/PI assay.2 Effects of brazilin on depressive and anxiety-like behaviors in mice exposed to chronic mild stress.Sixty mice were randomly divided into na?ve group and CMS group,mice in na?ve group were raised without any stress and drug treatment.Mice in CMS groups were divided into 4 subgroups,vehicle group,brazilin treatment groups?3,10 mg/kg,i.p.?and fluoxetine group?10 mg/kg i.p.?.After a 28-day CMS procedure,mice were treated with vehicle,brazilin or fluoxetine once daily,followed by mild stress 30 min later for 7 continuous days.Behavioral test was performed to validate the effects of brazilin on CMS-induced depressive-and anxiety-like behaviors of mice 24 h after the last time of drug treatment.Results: 1 Protective effects of brazilin on H₂O₂-induced cellular injury 1.1 Data from MTS assays showed that H₂O₂ treatment induced significantly decreased of cell survival in a dose-dependent character.The concentration of 200 ?M of H₂O₂ was used to establish PC12 cell injury model in vitro.1.2 The results showed that brazilin treatment at relative lower doses had no significant effects on PC12 survival,while brazilin treatment at higher doses induced decreased cell survival,indicating the potential cytotoxicity of brazilin.The concentration of 0-40 ?M of brazilin were used for further investigation.1.3 Data from MTS assay showed that brazilin pretreatment at the concentration of 10 ?M?P<0.05?and 20 ?M?P<0.01?could significantly block H₂O₂-induced decrease of PC12 cell survival.1.4 Results from Annexin V-FITC/PI and flow cytometry showed that brazilin pretreatment at both concentration significantly reversed the H₂O₂-induced increase of apoptosis and necrosis ratios of PC12 cells?P<0.05?.2 Effects of brazilin on CMS-induced depressive-and anxiety-like behaviors in mice.The behavioral results indicated that CMS induced significant depressive-and anxiety-like behaviors.Mice exposed to CMS had decreased sucrose preference in the SPT?P<0.01?,enhanced latency to feeding in the NSF test?P<0.01?,and decreased time spent in central zone in the OFT?P<0.01?,compared with mice in na?ve group.Brazilin or fluoxetine treatment at 10mg/kg dose significantly reversed CMS-induced decrease of sucrose preference?P<0.01?without affecting the total intake?P>0.05?.Brazilin treatment at 3 mg/kg dose increased the decrease of time spent in central zone in the OFT test?P<0.05?.Both brazilin and fluoxetine treatment at 10mg/kg dose significantly reversed the increased latency time to feeding of mice exposed to CMS?P<0.05,P<0.01 respectively?,without affecting the total food intake in homecages in the NSF test?P>0.05?.Conclusion: The present data indicated that brazilin exerts significant antidepressantand anxiolytic-like effects in a chronic mild stress-induced depression mice model,which could be associated with its antioxidative activities.