RESUMEN
Objective To evaluate the effect of dezocine on cognitive function after sevoflurane anesthesia in a rat model of physiological stress.Methods Physiological stress was induced by applying repeated foot shock stimulation and confirmed by open field test.Thirty Spragne-Dawley rats with physiological stress,weighing 180-220 g,were divided into 3 groups (n=10 each) using a random number table:control group (group C),sevoflurane group (group S) and dezocine plus sevoflurane group (group D+S).Normal saline 0.5 ml was intraperitoneally injected at 6 h of oxygen inhalation in group C.Normal saline 0.5 ml was intraperitoneally injected at 6 h of 3.0％ sevoflurane inhalation in group S.Dezocine 3 mg/kg was intraperitoneally injected at 6 h of 3.0％ sevoflurane inhalation in group D+S.At 1,12,24 and 48 h after the end of intraperitoneal injection (T1-4),Morris water maze test was performed,and the time of staying at the original platform quadrant and frequency of crossing the original platform were recorded.The rats were sacrificed after the end of Morris water maze test,brains were removed and hippocampi were isolated for determination of nitric oxide synthase-1 (nNOS) expression (by Western blot) and nNOS positive cells (by immunohistochemistry).Results Compared with group C,the time of staying at the original platform quadrant was significantly shortened at T1,2,the frequency of crossing the original platform was reduced at T1,the expression of nNOS in hippocampus was down-regulated,and the number of nNOS positive cells in hippocampal CA1 region was reduced in group S (P＜0.05),and no significant change was found in the parameters mentioned above in group D+S (P＞0.05).Compared with group S,the time of staying at the original platform quadrant was significantly prolonged at T1,the frequency of crossing the original platform was increased at T1,2,the expression of nNOS in hippocampus was up-regulated,and the number of nNOS positive cells in hippocampal CA1 region was increased in group D+S (P＜0.05).Conclusion Dezocine can improve cognitive function after sevoflurane anesthesia in a rat model of physiological stress,and the mechanism may be related to up-regulating nNOS expression in hippocampi.