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Objective To investigate the effect of melatonin on isoflurane anesthesia-induced cognitive dysfunction in aged rats.Methods Seventy-five male SD rats,aged 18-20 months,weighing 350-400 g,were randomly assigned into 5 groups(n =15 each):control group(group C),1.5％ isoflurane group(group Ⅰ),melatonin 5 mg/kg group(group M1),melatonin 10 mg/kg group(group M2)and melatonin 20 mg/kg group(group M3).Group G inhaled a gas mixture of oxygen and air for4 h and group 1 inhsled 1.5％ isoflurane for4 h.Melatonin 5,10 and 20 mg/kg(in normal saline containing 1％ DMSO)were injected intrsperitoneally at 15 min before anesthesia and 3 h after the beginning of anesthesia in groups M1,M2 and M3 respectively,and then the animals inhaled 1.5％ isoflurane for 4 h.At the end of anesthesia,5 rats in each group were chosen and blood samples were taken to perform arterial blood gas analysis and to detect the blood glucose level and expression of phosphorylated Tau(p-Tau)protein in hippocampus.Ten rats in each group were chosen at 14 d after the end of anesthesia and Morris water maze was performed 3 times a day for 5 consecutive days to assess the cognitive function.Then the animals were sacrificed and hippocampi were removed for detection of p-Tau expression by Western blot.Results There were no significant differences in the parameters of arterial blood gas analysis and blood glucose level among the 5 groups(P ＞ 0.05).Compared with group C,the escape latency at 3-5 d was significantly prolonged,the probe time was significantly shortened,and the expression of p-Tau protein was up-regulated in groups I and M1(P ＜0.05),and no significant change was found in the indexes mentioned above in groups M2 and M3 (P ＞0.05).Compared with groups 1 and M1,the escape latency at 2-5 d was significantly shortened,the probe lime was significantly prolonged,and the expression of p-Tau protein was down-regulated in groups M2 and M3 (P ＜ 0.05).There were no significant differences in the indexes mentioned above between groups I and M1,and between groups M2 and M3(P ＞ 0.05).Conclusion Melatonin(10 and 20 mg/kg)can improve isoflurane anesthesia-induced cognitive dysfunclion in aged rats,which nay be related to inhibition of hyperphosphorylation of Tau protein in hippocampus.
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Objective To compare the severity of hepatic ischemidreperfusion(I/R)injury caused by partial hepatectomy performed under propofol-remifentanil and isoflurane-fentanyl anesthesia.Methods Thirty ASA Ⅰ or Ⅱ patients aged 41-64 yr weighing 58-86 kg undergoing elective partial hepatectomy were randomly divided into 2 groups(n=15 each):propefol-remifentanil group(PR)and isoflurane-fentanyl group(IF).Anesthesia was induced with midazolam,fentanyl,etomidate and vecuronium.The patients were mechanically ventilated after tracheal intubation.Anesthesia was maintained with TCI of propofol(Cp=3.5μg/ml)and remifentanil(Cp=4.2 ng/ml)in group PR or 1.5%-2.5% isoflurane and intermittent iv boluses of fentanyl in group IF.Muscle relaxation was maintained with intermittent iv boluses of vecuronium in both groups.Blood samples were taken before occlusion of hepatic portal(T1)immediately(T2)and 30,60 min after release of portal occlusion(T3,4)and 1 d after operation(T5),for determination of sernm levels of ALT,AST,γ-GGT,LDH,TBIL,T-SOD and MDA.Specimens were obtained from the liver left intact after partial hepatectomy for ultrastructural examination with electron microscope.ResultsSerum levels of ALT at T5,γ-GGT at T3,4,and MDA at T4,5 were significandy lower while T-SOD at T5 were significantly higher in group PR than in group IF.Electron microscopic examination showed that tissue damages were significantly aRenuated in PR group as compared with IF group.Conclusion Propofol-remifentanil anesthesia can to some extent pmtect the liver against I/R injury during partial hepatectomy by reducing oxygen free radicals.