The Role Of Endoplasmic Reticulum Stress And Mitochondrial Apoptosis Pathway In Ketamine-induced Hippocampal Injury In Rats

Objective: By establishing animal models of different degrees of hippocampus injury,we will further systematically analyze the effects of endoplasmic reticulum stress and mitochondrial apoptosis pathways in ketamine-induced hippocampal injury in rats.It is expected to provide data for the study of the mechanism of hippocampal damage caused by ketamine.Methods: Sixty male SD rats(10 weeks old)were randomly divided into 4 groups(n=15): the control group,K10,K30 and K60 groups.K10,K30 and K60 groups were respectively given 10mg/kg,30mg/kg and 60mg/kg intraperitoneal injections of ketamine once a day for 4 weeks.The control group was treated with normal saline(1ml/kg).Monitor rat body weight weekly to adjust dosage.Twenty-four hours after the last administration at the end of the 4th week,the hippocampus tissue of each group of rats was subjected to HE staining pathological examination and transmission electron microscopy.Western blotting(WB)and q PCR technology were respectively used to detect the expression of key signals(GRP78,PERK,e IF-2a,ATF4,CHOP and Caspase12)of endoplasmic reticulum stress pathway,mitochondrial functional status indicators(DRP1,OPA1)and key signals(P53,BCL-2 and Caspase3)of mitochondrial apoptosis pathway.Results:1.Changes in weight of rats before and after administration: Compared with the control group,there was no significant difference in the weight gain of the K10 group,while the weight gain of the K30 and K60 groups was significantly reduced(P<0.05).2.Histopathological examination results of hippocampus: the hippocampal nerve cells of the control group were full,with tightly arranged cells and clear structure;in each treatment group,the number of nerve cell layers decreased,and the nerve cell arrangement was sparse and disordered.3.Ultrastructure of hippocampal nerve cells: a large number of rough endoplasmic reticulum can be shown in the cytoplasm of hippocampal nerve cells in the control group.The ribosomes are evenly distributed,the mitochondria are larger,and the cristae are obvious.However,different levels of endoplasmic reticulum appeared in each treatment group.Degranulation and swelling,mitochondria become smaller.4.q PCR and WB results:The expression of key signals(GRP78,PERK,e IF-2a,ATF4,CHOP and Caspase12)of the endoplasmic reticulum stress pathway increased to varying degrees in the K30 and K60 groups,but in the K10 group,although the expression of GRP78,PERK and e IF-2a were also higher than that of the control group,while the expressions of ATF4,CHOP and Caspase12 were not significantly difference compared with the control group.The expression of pro-apoptotic signals(DRP1,P53,and Caspase3)of the mitochondrial apoptotic pathway in the K30 and K60 groups all increased to varying degrees,whereas the expression of anti-apoptotic signals(OPA1 and BCL-2)in the K30 and K60 groups decreased to varying degrees.However,the expression trends of the above signals in the K10 group were opposite to those in the K30 and K60 groups.Conclusion: The administration of 10 mg/Kg ketamine can only cause mild endoplasmic reticulum stress in the hippocampus of rats and avoid damage to hippocampal nerve cells.The administration of 30mg/Kg and 60mg/Kg of ketamine can cause severe endoplasmic reticulum stress in the hippocampus of rats,which may cause hippocampal cell apoptosis through the GRP78/PERK/e IF-2a/ATF4/CHOP and Caspase12 pathways.At the same time,the apoptosis signals are transmitted to mitochondria,breaking the balance of mitochondrial division/fusion,and aggravating hippocampal damage in rats by regulating the expression of various signal molecules in the P53/BCL-2/Caspase3 pathway.