Evaluation Of The Depressive-like Behavior Following Local Anesthetic-induced Convulsion In Mice And The Therapeutic Effect And Mechanism Of Minocycline

Objective To establish a mouse model of convulsion induced by ropivacaine and evaluate the occurrence and development of its depression-like behavior,and to study the therapeutic effect and mechanism of minocycline on ropivacaine-induced convulsion-like behavior in mice.Methods(1)The convulsion model was established by intraperitoneal injection of ropivacaine in mice,and the open field test was used to evaluate the motor ability of mice after convulsion.(2)Novelty-suppressed feeding test,tail suspension test and forced swim test were used to evaluate the occurrence and duration of depression-like behavior in mice after convulsion.(3)Immunofluorescence staining was used to detect the dynamic changes of microglial marker ionized calcium binding adaptor molecule-1(Iba-1)expression in hippocampus.(4)Minocycline was injected intraperitoneally for three consecutive days immediately after convulsion in mice,and the effect of minocycline on depression-like behavior in mice after convulsion was evaluated.(5)The effect of minocycline on the expression of ionized calcium binding adaptor molecule-1(Iba-1),a microglial marker,in hippocampus was observed by immunofluorescence staining.(6)The effect of minocycline on the expression of inflammatory factors IL-1β,IL-6 and TNF-α in hippocampus was detected by ELISA method.Results(1)After intraperitoneal injection of ropivacaine,there was no significant gender difference in the latency and duration of convulsions between female and male mice.(2)Compared with the non-convulsion group,both female and male mice showed depression-like behavior after convulsion,in which the depression-like behavior of male mice was obvious on the 1st and 3rd day after convulsion,and gradually relieved on the 7th day after convulsion.On the other hand,the depression-like behavior of female mice was significant on the 1st,3rd and 7th day after convulsion,and began to relieve gradually on the 14 th day.(3)Compared with the non-convulsion group,the number of microglia in the hippocampus(CA1,CA3 and DG)of female and male mice increased significantly after convulsion,showing a significant enhancement of Iba-1 immunofluorescence reaction.The microglia in the hippocampus of male mice began to activate on the first day after convulsion,reached the peak on the third day,and returned to normal on the 7th day.However,the microglia in the hippocampus of female mice were significantly activated on the 1st,3rd and 7th day after convulsion,and returned to the baseline level on the 14 th day after convulsion.(4)The results of correlation analysis showed that the number of activated microglia in the hippocampus of convulsive mice was significantly correlated with depression-like behavior after convulsion.(5)Compared with normal mice and non-convulsive mice,there was no significant change in the total movement distance of female and male mice in the open field after convulsion,suggesting that ropivacaine-induced convulsion had no significant effect on the motor ability of mice.(6)Intraperitoneal injection of minocycline had no significant effect on the duration of convulsion induced by ropivacaine in mice.(7)Continuous intraperitoneal injection of minocycline could significantly improve the depression-like behavior of female and male mice on the 3rd day after convulsion induced by ropivacaine.(8)Continuous intraperitoneal injection of minocycline significantly inhibited the activation of microglia in the hippocampus of female and male mice after convulsion.(9)Minocycline can significantly reduce the expression of inflammatory factors IL-1β,IL-6 and TNF-α in the hippocampus of female and male mice after convulsion.Conclusion(1)After convulsion induced by ropivacaine,both female and male mice showed significant depression-like behavior,and the depression-like behavior of female mice lasted longer.(2)The microglia in the hippocampus of female and male mice were significantly activated after convulsion induced by ropivacaine,and the number of microglia was closely related to the occurrence of depression-like behavior.(3)Continuous intraperitoneal injection of minocycline could significantly inhibit the activation of microglia and down-regulate the expression of inflammatory factors IL-1β,IL-6 and TNF-α in hippocampus of female and male mice after convulsion,thus improving the depressive behavior of female and male mice after convulsion induced by ropivacaine.