The Effect And Mechanism Of GLYX-13 On Cognitive Function In Mice After Long-time Isoflurane Anesthesia

Objective:To clarify the effect of pre-treatment of N-methyl-D-aspartate glutamate receptor glycine site agonist GLYX-13 on cognitive function in mice after long-time isoflurane anesthesia and to explore the mechanism of protective effect of GLYX-13 on cognitive function.Methods: 8 to 10-week-old male C57/BL-6J mice were used in this study and randomly divided into 4 groups: control group(Con),isoflurane anesthesia group(Anes),GLYX-13 group(GLYX-13)and isoflurane anesthesia + GLYX-13 group(Anes+GLYX-13).GLYX-13 group and Anes+GLYX-13 group of mice were given GLYX-13(1mg/kg)through intravenously injection 2 hours before isoflurane anesthesia,Con group and Anes group of mice were injected an equal volume of saline.Anes group and Anes+GLYX-13 group of mice were exposed to isoflurane 6 hours.Contextual fear conditioning memory test and novel object recognition test were performed to examine the cognitive function of mice on the 1,3 and 7 days after isoflurane anesthesia.Western blot and real-time polymerase chain reaction(QPCR)were performed to determine the phosphorylated protein and m RNA expression of N-methyl-D-aspartate receptor subunit 2B(NR2B),calcium/calmodulin-dependent protein kinase II(Ca MKII)and c AMP-response element binding protein(CREB).Further,to clarify the mechanism of GLYX-13,mice were randomly assigned to four groups and given a Ca MKII specific inhibitor KN93: isoflurane anesthesia group(Anes),isoflurane anesthesia + GLYX-13 group(Anes+GLYX-13),isoflurane anesthesia + KN93 group(Anes+KN93)and isoflurane anesthesia + GLYX-13 + KN93 group(Anes+GLYX-13+KN93).Anes+KN93 group and Anes+GLYX-13+KN93 group of mice were injected with 1 mmol KN93 through the lateral ventricle 4 hours before isoflurane anesthesia;Anes+GLYX-13 group and Anes+GLYX-13+KN93 group of mice were injected with GLYX-13(1 mg/kg)through the tail vein 2 hours before isoflurane anesthesia.Each group of mice received isoflurane anesthesia for 6 hours.Western blot and QPCR were performed to determine the phosphorylated protein and m RNA expression levels of NR2 B,Ca MKII and CREB on the 1,3 and 7 days after isoflurane anesthesia.Contextual fear conditioning memory test and novel object recognition test were performed to examine the cognitive function of mice.Results: Long-time isoflurane anesthesia resulted in cognitive impairment in contextual fear conditioning memory test and novel object recognition test,accompanied by decreased in phosphorylated protein and m RNA expression level of NR2 B,Ca MKII,and CREB in the hippocampus of mice.Pre-treatment with GLYX-13 attenuated cognitive impairment in mice which exposed to long-time isoflurane anesthesia in contextual fear conditioning memory test and novel object recognition test,and up-regulated phosphorylated protein and m RNA expression of NR2 B,Ca MKII,and CREB in hippocampus of mice.Combined administration of KN93,a Ca MKII-specific inhibitor,blocked GLYX-13 from improving cognitive function and up-regulating phosphorylated protein and m RNA of NR2 B,Ca MKII,and CREB in hippocampus of mice.Conclusions: Pre-treatment with GLYX-13 can attenuate cognitive impairment in mice after long-time isoflurane anesthesia and NR2B-Ca MKII-CREB signaling pathway may be involved.