褪黑素对异氟醚麻醉大鼠海马胆碱乙酰基转移酶的影响

Objective To investigate the effects of melatonin on choline acetyltransferase (ChAT) in the hippocampus of rats after isoflurane anesthesia.Methods Sixty male SD rats weighing 390-440 g were randomized into five groups (n =12 each):control group (group C),1％ isoflurane group (group Ⅰ),1％ isoflurane + melatonin group (group IM),2％ isoflurane group (group J) and 2％ isoflurane + melatonin group (group JM).Rats in groups IM and JM received intraperitoneal injection of melatonin (10 mg/kg) for 7 days,and rats in other groups received normal saline.On the 7th day of injection,rats in groups Ⅰ and IM inhaled 1％ isoflurane for 4 hours,and rats in groups J and JM inhaled 2％ isoflurane for 4 hours.One day after anesthesia,all the rats began Morris water maze to assess the learning and memory ability,which was made for continuous 5 days.At the end of probe test,6 rats in each group were randomly selected,blood samples were collected to detect plasma melatonin level,and the hippocampi were removed to evaluate the expression and activity of ChAT.The other rats were sacrificed to perform immunofluorescence to detect ChAT in hippocampal CA1 region and dentate gyrus.Results The plasma melatonin level,and the expression and activity of ChAT were significantly lower in group Ⅰ than in group C (P ＜ 0.01).The escape latency was significantly longer,the probe time was significantly shorter,and the plasma melatonin level and the expression and activity of ChAT were significantly lower in group J than in group C (P ＜ 0.05 or 0.01).The escape latency was significantly shorter,the probe time was significantly longer,and the plasma melatonin level and the expression and activity of ChAT were significantly higher in group IM than in group Ⅰ (P ＜ 0.05 or 0.01).The escape latency was significantly shorter,and the plasma melatonin level and the ChAT activity were significantly higher in group JM than in group J (P＜ 0.05 or 0.01).Conclusion Melatonin can attenuate isoflurane-induced ChAT inhibition and thus improve the cognitive function of rats after isoflurane anesthesia.