Objective:To investigate the effects and potential mechanisms of melatonin on cognitive dysfunction induced by long-term anesthesia with isoflurane.Methods:Male C57BL/6J mice aged 2 months were divided into control group, isoflurane group, melatonin group, and isoflurane+ melatonin group by random number table, with 6 mice in each group.Three days after anesthesia, cognitive function of mice was assessed by Y-maze and fear conditioning (FC) tests. ATP content in the hippocampus was measured by an ATP assay kit. Western blot was used to detect the expression of DRP1, pDRP1, MFN2, pAMPK and SIRT1 proteins in the hippocampus. Cultured HT-22 cells derived from mouse hippocampal neurons in vitro were divided into control group, isoflurane group, melatonin group, and isoflurane + melatonin group, and the levels of reactive oxygen species (ROS) in each group were detected by flow cytometry after intervention. Statistical analysis was performed by SPSS 22.0 software, and one-way ANOVA was used for comparisons among multiple groups.Results:(1) There was a statistically significant difference in the percentage of freezing behavior in contextual fear memory among the four groups of mice ( F=39.09, P<0.05). The percentage of freezing behavior in the isoflurane group was lower than that in the control group ((44.23±8.88)% vs (75.87±5.90)%, P<0.05), while the percentage of freezing behavior in the isoflurane+ melatonin group((67.45±14.89)%)was higher than that in the isoflurane group ( P<0.05). There was also a statistically significant difference in the percentage of exploration in the novel arm among the four groups of mice ( F=13.87, P<0.05). The percentage of exploration in the novel arm in the isoflurane group was lower than that in the control group((33.64±6.53)% vs (47.13±3.87)%, P<0.05), while the percentage of exploration in the novel arm in the isoflurane+ melatonin group((43.05±1.64)%)was higher than that in the isoflurane group ( P<0.05). (2) Statistically significant difference in the levels of ATP in the hippocampus was found among the four groups of mice ( F=49.22, P<0.05). The level of ATP in the hippocampus in the isoflurane group was lower than that in the control group((2.29±0.15)nmol/mg vs (3.58±0.12)nmol/mg, P<0.05), while the level of ATP in the hippocampus in the isoflurane+ melatonin group ((3.02±0.27)nmol/mg)was higher than that in the isoflurane group ( P<0.05). There was a statistically significant difference in the levels of ROS in HT-22 cells among the four groups ( F=18.36, P<0.05). The level of ROS in HT-22 cells in the isoflurane group was higher than that in the control group after anesthesia ( P<0.05), while the level of ROS in HT-22 cells in the isoflurane+ melatonin group was lower than that in the isoflurane group after anesthesia ( P<0.05). (3) There were statistically significant difference in the levels of pDRP1, pAMPK and SIRT1 protein in the hippocampus among the four groups of mice ( F=19.87, 21.20, 25.65, all P<0.05). The levels of pDRP1 and SIRT1 protein in the hippocampus in the isoflurane group were both lower than those in the control group (both P<0.05), while the levels of pDRP1 and SIRT1 protein in the hippocampus in the isoflurane+ melatonin group were both higher than those in the isoflurane group (both P<0.05). In the isoflurane group, the expression of pAMPK protein in the hippocampal region was higher than that in the control group ( P<0.05), while the expression of pAMPK protein in the isoflurane+ melatonin group was lower than that in the isoflurane group ( P<0.05). Conclusion:Melatonin improves long-term isoflurane anesthesia-induced cognitive dysfunction by regulating mitochondrial homeostasis through the AMPK/SIRT1 signaling pathway.

Objective:To investigate the effects and potential mechanisms of melatonin on cognitive dysfunction induced by long-term anesthesia with isoflurane.Methods:Male C57BL/6J mice aged 2 months were divided into control group, isoflurane group, melatonin group, and isoflurane+ melatonin group by random number table, with 6 mice in each group.Three days after anesthesia, cognitive function of mice was assessed by Y-maze and fear conditioning (FC) tests. ATP content in the hippocampus was measured by an ATP assay kit. Western blot was used to detect the expression of DRP1, pDRP1, MFN2, pAMPK and SIRT1 proteins in the hippocampus. Cultured HT-22 cells derived from mouse hippocampal neurons in vitro were divided into control group, isoflurane group, melatonin group, and isoflurane + melatonin group, and the levels of reactive oxygen species (ROS) in each group were detected by flow cytometry after intervention. Statistical analysis was performed by SPSS 22.0 software, and one-way ANOVA was used for comparisons among multiple groups.Results:(1) There was a statistically significant difference in the percentage of freezing behavior in contextual fear memory among the four groups of mice ( F=39.09, P<0.05). The percentage of freezing behavior in the isoflurane group was lower than that in the control group ((44.23±8.88)% vs (75.87±5.90)%, P<0.05), while the percentage of freezing behavior in the isoflurane+ melatonin group((67.45±14.89)%)was higher than that in the isoflurane group ( P<0.05). There was also a statistically significant difference in the percentage of exploration in the novel arm among the four groups of mice ( F=13.87, P<0.05). The percentage of exploration in the novel arm in the isoflurane group was lower than that in the control group((33.64±6.53)% vs (47.13±3.87)%, P<0.05), while the percentage of exploration in the novel arm in the isoflurane+ melatonin group((43.05±1.64)%)was higher than that in the isoflurane group ( P<0.05). (2) Statistically significant difference in the levels of ATP in the hippocampus was found among the four groups of mice ( F=49.22, P<0.05). The level of ATP in the hippocampus in the isoflurane group was lower than that in the control group((2.29±0.15)nmol/mg vs (3.58±0.12)nmol/mg, P<0.05), while the level of ATP in the hippocampus in the isoflurane+ melatonin group ((3.02±0.27)nmol/mg)was higher than that in the isoflurane group ( P<0.05). There was a statistically significant difference in the levels of ROS in HT-22 cells among the four groups ( F=18.36, P<0.05). The level of ROS in HT-22 cells in the isoflurane group was higher than that in the control group after anesthesia ( P<0.05), while the level of ROS in HT-22 cells in the isoflurane+ melatonin group was lower than that in the isoflurane group after anesthesia ( P<0.05). (3) There were statistically significant difference in the levels of pDRP1, pAMPK and SIRT1 protein in the hippocampus among the four groups of mice ( F=19.87, 21.20, 25.65, all P<0.05). The levels of pDRP1 and SIRT1 protein in the hippocampus in the isoflurane group were both lower than those in the control group (both P<0.05), while the levels of pDRP1 and SIRT1 protein in the hippocampus in the isoflurane+ melatonin group were both higher than those in the isoflurane group (both P<0.05). In the isoflurane group, the expression of pAMPK protein in the hippocampal region was higher than that in the control group ( P<0.05), while the expression of pAMPK protein in the isoflurane+ melatonin group was lower than that in the isoflurane group ( P<0.05). Conclusion:Melatonin improves long-term isoflurane anesthesia-induced cognitive dysfunction by regulating mitochondrial homeostasis through the AMPK/SIRT1 signaling pathway.

Objective To investigate the effects of dehydrocorydaline(DHC) on complete Freund's adjuvant (CFA)-induced mechanical hyperalgesia in mice.Methods 40 mice were divided randomly into 4 groups (CFA test:experiment group =8,control group =8;locomotor activity and organ coefficient test:experiment group=12,control group =12).Subcutaneously injected CFA in the plantar of mice to establish pain model.The experimental group mice were injected with 10 mg/kg DHC while the control group mice received 10％ DMSO.The paw withdrawal mechanical threshold(PWMT) of mice was tested before and after administration of DHC.The effects of DHC on spontaneous activity and organ coefficient were observed in mice.Results The basic values of PWMT showed there were no statistically significant differences between experimental group and control group ((10.27± 1.34)g vs (10.28 ±0.35)g,P＞0.05).Compared with the control group,the values of PWMT in experimental group at 0.5 h,1 h,2 h,3 h after administration of DHC were significantly increased(0.5 h:(8.18±0.87) g vs (4.85±0.65) g;1 h:(7.85±0.59) g vs (4.84±0.54) g;2 h:(7.36±0.49) g vs (4.90±0.59) g;3 h:(6.66±0.45) g vs (5.00±0.36) g;all P＜0.01).Compared with the control group,no significant effect was observed on the number mice crossed grids and lifted forelimb and stood in 2 min in the experimental group (P＞ 0.05).And no significant effect was observed on the liver,kidney,spleen,heart,lung and brain organ coefficient in the experiment group (P＞0.05).Conclusion DHC can alleviate CFA-induced mechanical hyperalgesia in mice.