Effects And The Related Mechanism Of Propofol On Neuronal Cell Proliferation Of Hippocampus With Injury After Transient Forebrain Ischemia In Gerbils

PartⅠEffects of propofol on neuronal cell proliferation of hippocampus with injury after transient forebrain ischemia in gerbilsObjective This study aimed to explore propofol's effect on neuronal cell proliferation of hippocampus in adult gerbils with injury after transient forebrain ischemia.This could provide theoretical basis for clinical rational use and study of propofol,and provide basis for further study of the mechanism of propofol's effect on neuronal cell proliferation.Method 40 adult gerbils were randomly divided into five groups:sham group(without occlusion of bilateral carotid artery), ischemia group(with 10 min occlusion of bilateral carotid artery),10 mg/kg propofol group(with 10 min occlusion of bilateral carotid artery and intraperitoneal injection of propofol 10 mg/kg/12h for 9 days),50 mg/kg propofol group(with the similar treatment but the dosage of propofol was 50 mg/kg/12h), and 100 mg/kg propofol group(with the similar treatment but the dosage of propofol was 100 mg/kg/12h).Each group has eight gerbils,and was observed at four time points(1^rd day,8^th day,15^th day and 22^th day after ischemia).At each pointed,two gerbils were sampled,and were administered intraperitoneal injection of BrdU 100 mg/kg/12h for 2 days,then trans-cardiac perfusion began with physiological saline solution,and followed by 4%paraformaldehyde.After perfusion,the brains were processed and embedded in paraffin.Serial 10μm sections were administered with BrdU immunohistostaining.BrdU-labelled cells of the hippocampus dentate gyrus were counted.Results 1) Compared with the sham group,the number of BrdU-labelled cells of hippocampus dentate gyrus in the ischemia group,10 mg/kg propofol group,50 mg/kg propofol group,and 100 mg/kg propofol group,had no significant change.2) 10 days after ischemia,the number of BrdU-labelled cells of hippocampus dentate gyrus in the ischemia group started to increase(P＜0.05) and reached the peak 17 days after ischemia (P＜0.05);10 days after ischemia,the number of BrdU-labelled cells of hippocampus dentate gyrus in the 10 mg/kg propofol group was significantly higher than that of the ischemia group(P＜0.05),and was significantly higher than that of the ischemia group 17 days after ischemia(P＜0.05),with the peak time brought forward to the 10^th day after ischemia.3) 10 days,17 days and 24 days after ischemia,the number of BrdU-labelled cells of hippocampus dentate gyrus in the 50 mg/kg propofol group and 100 mg/kg propofol group were significantly higher than that of 3 days after ischemia(P＜0.05),and significantly lower than that of the 10 mg/kg propofol group at the same time point(P＜0.05).17 days after ischemia,the number of BrdU-labelled cells of hippocampus dentate gyrus in the 50 mg/kg propofol group and 100 mg/kg propofol group was substantially lower than that of the ischemia group(P＜0.05),however,10 days and 24 days after ischemia,the numbers had no significant change.Conclusions Intraperitoneal injection of propofol 10 mg/kg/12h may promote ischemia-induced neuronal cell proliferation of hippocampus in gerbils and brings the peak time of neuronal cells proliferation forward,and intraperitoneal injection of propofol 50 mg/kg/12h and 100 mg/kg/12h inhibited ischemia-induced neuronal cell proliferation.PartⅡReceptor mechanism of propofol on promoting neuronal cell proliferation of hippocampus with injury after transient forebrain ischemia in gerbilsObjective To investigate the receptor mechanism of propofol's promotive effect on ischemia-induced neuronal cell proliferation of hippocampus in gerbil model that had transient forebrain ischemic injury.Method 60 adult gerbils were randomly divided into 10 groups:sham group,ischemia group,fat emulsion group, bicuculline group,MK801 group,bicuculline+MK801 group,propofol group, Bicuculline+propofol group,MK801+propofol group,and bicuculline+MK801 +propofol group.Each group had six gerbils,and each received 9 days' intraperitoneal injection with respective medicine.Then each group was randomly divided into BrdU sub-group and amino acid sub-group,each sub-group had three gerbils.The gerbils in the BrdU sub-group started to receive intraperitoneal injection of BrdU 100 mg/kg/12h from the 8^th day.After 2 days' injection,transcardiac perfusion began with physiological saline solution,and followed by 4% paraformaldehyde.After perfusion,the brains were then processed and embedded in paraffin.Serial 10μm sections were administered with BrdU immunohisto-staining. BrdU-labelled cells of the hippocampus dentate gyrus were counted.On the 10^th day after ischemia,the hippocampus of gerbils in the amino acid sub-group was dissected for analyzing the concentration of neurotransmitter of aspartic acid,glutamic acid,glycine and gamma-aminobutyric acid by the high performance liquid chromatography.Results 1) Compared with the sham group, the ischemia group underwent no significant change in the number of BrdU-labelled cells of hippocampus dentate gyrus;compared with the ischemia group, the number of BrdU-labelled cells of hippocampus dentate gyrus in the fat emulsion group,bicuculline group,MK801 group and bicuculline+MK801 group had no significant change.2) Compared with the ischemia group,the number of BrdU-labelled cells of hippocampus dentate gyrus of the propofol group significantly increased(P＜0.05).3)The number of BrdU-labelled cells of hippocampus dentate gyrus in the bicuculline+propofol group,MK801+propofol group,and bicuculline+MK801+propofol group significantly decreased compared with the propofol group(P＜0.05),and had no significant change compared with the ischemia group.4) For neurotransmitter concentration of aspartic acid,glutamic acid,glycine and gamma-aminobutyric acid in the hippocampus tissue,there are no significant difference among the groups. Conclusions Intraperitoneal injection of propofol 10 mg/kg/12h may promote ischemia-induced neuronal cell proliferation of hippocampus in gerbils,and its promoting effect on the hippocampus neuronal cells proliferation can be reversed by bicuculline and MK801.Intraperitoneal injection of propofol 10 mg/kg/12h had no marked effect on the neurotransmitter concentration of amino acid of hippocampus in gerbils 10 days after transient forebrain ischemia.PartⅢEffects of propofol on GABA_A receptor mRNA expression of hippocampus in gerbils after transient forebrain ischemiaObjective To investigate the possible mechanism of propofol on promoting neuronal cell proliferation of hippocampus in gerbils that has injury after transient forebrain ischemia by administrating propofol with GABA_A receptor antagonist and NMDA receptor antagonist,observing propofol's effects on expression of hippocampus GABA_A receptor mRNA,and observing changes in propofol effect on expression of GABA_A receptor mRNA with respective antagonizing and simultaneous antagonizing of GABA_A receptor and NMDA receptor.Method 30 adult gerbils are randomly divided into 10 groups:sham group,ischemia group, fat emulsion group,bicuculline group,MK 801 group,bicuculline+MK 801 group, propofol group,bicuculline+propofol group,MK801+propofol group,and bicuculline+MK801+propofol group.Each group had three gerbils,and received 9 days' intraperitoneal injection with respective medicine.On the 10th day after ischemia,the hippocampus was dissected.The real-time fluorescence quantitative RT-PCR was administrated to analyse the hippocampus GABA_A receptor mRNA expression.Results 1) Compared with the sham group,the gene expression of GABA_A receptor mRNA of the ischemia group,the fat emulsion control group, the bicuculine control group,the MK801 control group,the bicuculine+MK801 group had no significant change.2) Compared with the ischemia group,the gene expression of GABA_A receptor mRNA of the propofol group increasd significantly(P＜0.05).Although compared with the ischemia group,the gene expression of GABA_A receptor mRNA in the bicuculline+propofol group,the MK801+propofol group and the bicuculline+MK801+propofol group had no significant difference,they were significantly lower than that of the propofol group(P＜0.05).Conclusions Intraperitoneal injection of 10 mg/kg/12h propofol may significantly increase GABA_A receptor mRNA expression of hippocampus in gerbils with injury after transient forebrain ischemia,and its effect can be reversed by bicuculline and MK801.