| [Background]Depression is one of the most common mental disorders in modern society,which belongs to the category of "depression syndrome" in traditional Chinese medicine.The main manifestations are persistent depression,lack of interest,decreased activity,sleep disorders and so on.Severe cases have obvious cognitive impairment and suicidal tendency.Clinical studies show that acupuncture is a convenient treatment with less side effect,high acceptance of patients,and has a significant effect on depression.In-depth study about the mechanism of acupuncture in the treatment of depression has important medical value and social significance.In recent years,neuroinflammation has received more attention in the study of the mechanism of depression.Chronic stress can cause immune inflammatory response,activate inflammatory body signal pathway,promote the maturation and secretion of inflammatory cytokines,and mediate pyroptosis.The activation of NLRP3 inflammasome signal pathway is an important factor in brain pyroptosis,inflammatory response and depression.Pyroptosis is a kind of programmed cell inflammatory death,which can eliminate inflammatory substances by releasing cell contents and inflammatory cytokines,but excessive pyroptosis will further expand the inflammatory response.NLRP3 inflammasome-mediated pyroptosis may play an important role in the mechanism of depression.Our previous study found that acupuncture can regulate the level of peripheral and central proinflammatory cytokines in rats with chronic stress depression.On the basis of previous work,this study explored the effect of acupuncture on pyroptosis mediated by NLRP3/Caspase-1/IL-18 signal pathway in prefrontal cortex of rats with chronic stress depression,so as to explain the antidepressant mechanism of acupuncture.[Objective]In this study,chronic stress depression rat model was used to observe the effects of acupuncture on behavior and pyroptosis mediated by NLRP3/Caspase-1/IL-18 signal pathway in prefrontal cortex ofrats with chronic stress,so as to further clarify the antidepressant mechanism of acupuncture,which provides a new train of thought and scientific basis for clinical acupuncture treatment of depression[Methods]1.Experimental animals and groups:32 SPF grade male Sprague-Dawley(SD)rats,weighing(200± 20)g,were randomly divided into the following four groups:blank group,model group,acupuncture group and fluoxetine group,with 8 rats in each group.2.Preparation method of chronic stress depression rat model:the depression rat model was established by chronic unpredictable mild stress.According to the intensity of one stimulus per day for 6 weeks,the following stimuli were randomly given:fasting for 24 hours,water deprivation for 24 hours,overnight lighting for 12 hours,strobe 2 hours,restraint 2 hours,tail 2 min,cold water swimming(water temperature 4?)5 min.3.Intervention methods:from the first day of modeling,the acupuncture group selected"Baihui" and "Yintang" points and received acupuncture treatment 1 hour before modeling stress,10 minutes each time,one day off every 6 days,a total of 36 times,and the animals in fluoxetine group were given by intragastric administration(10mg/kg)1 hour before daily modeling stress for 6 weeks4.Behavioral detection methods(1)Body weight:reflecting the general condition of rats,detected before and at the end of modeling.(2)Sucrose preference test:reflecting the loss of pleasure behavior in rats.It is detected before and at the end of the modeling5.Index detection(1)The protein expression of NLRP3 in rat prefrontal cortex was detected by Westernblot method;(2)The expression of Caspase-1 in rat prefrontal cortex was detected by immunohistochemical method.(3)The content of IL-18 in prefrontal cortex was detected by enzyme-linked immunosorbent assay(ELISA)(4)The expression of pyroptosis in rat prefrontal cortex was detected by TUNEL method.6.Statistical methods:the experimental data were counted by statistical software,and the results were expressed by mean±standard deviation(X±SD).One-way ANOVA was used to analyze the data,which showed that the difference was significant(P<0.05).[Results]1.The effect of acupuncture on the behavior of rats:(1)Body weight:There was no significant difference in body weight among the three groups before modeling(P>0.05),but after modeling,the body weight in the model group was significantly lower than that in the blank group(P<0.05).Compared with the model group,the body weight increased in acupuncture group and fluoxetine group,but there was no significant difference(P>0.05).There was no significant difference in body weight between acupuncture group and fluoxetine group(P>0.05)(2)Sucrose preference test:There was no significant difference in the percentage of sucrose preference among the rats in each group before modeling(P>0.05).After modeling,the percentage of sucrose preference in the model group was significantly lower than that in the blank group(P<0.01),and the percentage of sucrose preference in the acupuncture group and fluoxetine group was significantly higher than that in the model group(all P<0.01).There was no significant difference in the percentage of sucrose preference between the acupuncture group and the fluoxetine group(P>0.05).2.Effect of acupuncture on the expression level of NLRP3 protein in prefrontal cortex of chronic stress depression model rats:Compared with the blank group,the expression level of NLRP3 protein in prefrontal cortex in model group was significantly higher than that in model group(P<0.01),while that in acupuncture group and fluoxetine group was significantly lower than that in model group(all P<0.01).There was no significant difference in the expression of NLRP3 protein between the acupuncture group and the fluoxetine group(P>0.05).3.Effect of acupuncture on the average optical density of Caspase-1 in prefrontal cortex of chronic stress depression model rats:Compared with the blank group,the average optical density of Caspase-1 positive cells in prefrontal cortex of model group was significantly higher than that of model group(P<0.01),while that of Caspase-1 positive cells in prefrontal cortex of acupuncture group and fluoxetine group was significantly lower than that of model group(all P<0.01).There was no significant difference in the average optical density of Caspase-1 positive cells in prefrontal cortex between acupuncture group and fluoxetine group(P>0.05).4.Effect of acupuncture on IL-18 content in prefrontal cortex of chronic stress depression model rats:Compared with blank group,IL-18 content in prefrontal cortex in model group was significantly higher(P<0.01),while IL-18 content in prefrontal cortex in acupuncture group and fluoxetine group was significantly lower than that in model group(all P<0.01).There was no significant difference in IL-18 content in frontal cortex between acupuncture group and fluoxetine group(P>0.05).5.Effect of acupuncture on the expression of TUNEL positive cells in prefrontal cortex of chronic stress depression model rats:Compared with the blank group,the number of TUNEL positive cells in the prefrontal cortex in the model group increased significantly(P<0.01),and compared with the model group,the number of TUNEL positive cells in prefrontal cortex decreased significantly in acupuncture group and fluoxetine group(all P<0.05).There was no significant difference in the number of TUNEL positive cells in prefrontal cortex between acupuncture group and fluoxetine group(P>0.05)[Conclusion]1.The body weight and sucrose preference percentage of chronic stress depression rats decreased significantly.Acupuncture and fluoxetine can increase the percentage of sucrose preference and improve the behavior of loss of pleasure,showing antidepressant effect2.The expression of NLRP3,Caspase-1 and IL-18 in the prefrontal cortex of chronic stress depression rats was significantly increased,and there was pyroptosis in the prefrontal cortex.Acupuncture and fluoxetine can inhibit the excessive activation of NLRP3 inflammatory bodies,reduce the expression of Caspase-1 and IL-18,and slow down the pyroptosis of cells.3.Acupuncture may reduce the inflammatory reaction and pyroptosis in the brain by inhibiting the activation of NLRP3 inflammatory corpuscle signal pathway in prefrontal cortex and down-regulating the expression of pyroptosis-related factors NLRP3,Caspase-1 and IL-18,so as to alleviate the brain damage caused by inflammation and play a role in the treatment of depression.This will provide an important scientific basis for clinical acupuncture treatment of depression. |
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