Effects Of Ketamine On Astrocytes In Cerebral Cortex Of Rats

Objective:To investigate the effects of ketamine on autophagy and apoptosis of astrocytes in the cerebral cortex of rats,and to determine whether nuclear factor-?B(NF-?B)pathway is involved in the regulation of autophagy and apoptosis of atrocytes.Materials and methods:A total of 36 male Sprague-Dawley rats were randomly divided into 3 groups:control group(Group C:intraperitoneal injection of equal amount of normal saline),glutamic acid group(Group G:intraperitoneal injection of 1 mg/kg glutamic acid)and glutamic acid+ketamine group(Group GK:intraperitoneal injection of 1 mg/kg glutamic acid and then injection of 5 mg/kg ketamine after 30 min).The cerebral cortex of rats in each group was taken after successive administration for 5 d.The number of glial fibrillary acidic protein(GFAP)-positive cells and LC3-positive cells in the cerebral cortex of rats in each group was detected via immunofluorescence.The number of apoptotic cells in the cerebral cortex was detected via TUNEL staining.The expression levels of inflammatory factors were detected using the enzyme-linked immunosorbent assay(ELISA)kit.Moreover,the expressions of autophagy-related proteins and apoptosis-related proteins in the cerebral cortex were detected via Western blotting,and the expressions of I?B-? and NF-?Bp65 were also detected.Results:(1)The results of immunofluorescence showed that the number of GFAP-positive cells in the cerebral cortex of rats in Group G was significantly increased compared with that in Group C(p<0.05),and it was significantly decreased in Group GK compared with that in Group G(p<0.05).GFAP+LC3 double staining results showed no significant difference between the three groups.(2)The results of TUNEL staining revealed that the number of TUNEL-positive cells in the cerebral cortex in Group G was significantly larger than that in Group C,and it was significantly smaller in Group GK than that in Group G(p<0.05).(3)Results of ELISA demonstrated that compared with those in Group C,the content of interleukin-6(IL-6)and tumor necrosis factor-?(TNF-?)in Group G was significantly increased(p<0.05),but the content of IL-10 was significantly decreased(p<0.05).Compared with those in Group G,the content of IL-6 and TNF-? in Group GK was lower(p<0.05),but the content of IL-10 was statistically elevated(p<0.05)(4)Western blotting:compared with those in Group C,the levels of LC3 ?/? and cleaved caspase-3 in the cerebral cortex in Group G were significantly increased(p<0.05),but the p62 level and B-cell lymphoma-2/Bcl-2 associated X protein(Bcl-2/Bax)ratio were significantly decreased(p<0.05).In Group GK,the levels of LC3?/? and cleaved caspase-3 were decreased,but the p62 level and Bcl-2/Bax ratio were increased.(5)The expressions of I?B-? and NF-?Bp65 in Group G were significantly decreased compared with those in Group C(p<0.05),and they were significantly higher in Group GK than those in Group G(p<0.05).Conclusion:Ketamine can reduce the glutamic acid-induced activation of astrocytes in the cerebral cortex,inhibit and alleviate the apoptosis of astrocytes,whose mechanism may be mediated by the NF-?B pathway.Ketamine can reverse glutamine-induced autophagy in cerebral cortex,but not in astrocytes.