瘦素对原位肝移植术大鼠脑损伤和远期认知功能的影响

Effects of leptin on brain injury and long-term cognitive function in rats undergoing orthotopic liver transplantation

目的评价瘦素对原位肝移植术大鼠脑损伤和远期认知功能的影响.方法清洁级雄性SD大鼠90只,3月龄,体重200~250g,采用随机数字表法分为3组(n=18):假手术组(S组)、肝缺血再灌注组(I∕R组)和瘦素组(L组).I∕R组和L组行原位肝移植术制备肝脏缺血再灌注损伤模型;L组于缺血即刻腹腔注射瘦素1mg∕kg,S组和I∕R组腹腔注射等容量生理盐水.术后3d时处死12只大鼠并取脑组织,光镜下观察海马CA1区病理学结果,采用TUNEL法检测海马神经元凋亡情况,计算凋亡率,Westernblot法检测海马水通道蛋白4(AQP4)和蛋白激酶C(PKC)的表达水平.余下6只大鼠于术后30d时进行Morris水迷宫实验评价远期认知功能.结果与S组比较,I∕R组和L组海马组织神经元凋亡率升高,AQP4和PKC表达上调,逃避潜伏期延长,平台所在象限滞留时间缩短(P<0.05);与I∕R组比较,L组海马组织神经元凋亡率降低,AQP4和PKC表达下调,逃避潜伏期缩短,平台所在象限滞留时间延长(P<0.05).结论瘦素可减轻原位肝移植术大鼠脑损伤,其机制可能下调PKC和AQP4的表达有关;瘦素还可改善原位肝移植术大鼠远期认知功能.

Objective To evaluate the effects of leptin on brain injury and long-term cognitive function in rats undergoing orthotopic liver transplantation.Methods Ninety clean-grade male Sprague-Dawley rats,aged 3 months,weighing 200-250 g,were divided into 3 groups by a random number table method:sham operation group(S group),liver ischemia-reperfusion(I/R)group(I/R group)and leptin group(L group),with 18 rats in each group.Orthotopic liver transplantation was performed to establish the model of liver I/R injury in I/R and L groups.Leptin 1 mg/kg was intraperitoneally injected at the onset of ischemia in L group,and the equal volume of normal saline was given instead of leptin in S and I/R groups.Twelve rats in each group were sacrificed at 3 days after operation,and brains were removed for examination of the pathological changes in hippocampal CA1 region(with a light microscope)and for determination of apoptosis in hippocampal neurons(by TUNEL assay)and expression of aquaporin 4(AQP4)and protein kinase C(PKC)in the hippocampus(by Western blot).The apoptosis rate was calculated.The remaining 6 rats in each group underwent a Morris water maze test at 30 days after surgery to evaluate long-term cognitive function.Results Compared with S group,the apoptosis rate of hippocampal neurons was significantly increased,the expression of AQP4 and PKC was up-regulated,the escape latency was prolonged,and the time of staying at the platform quadrant was shortened in I/R and L groups(P<0.05).Compared with I/R group,the apoptosis rate of hippocampal neurons was significantly decreased,the expression of AQP4 and PKC was down-regulated,the escape latency was shortened,and the time of staying at the platform quadrant was prolonged in L group(P<0.05).Conclusion Leptin can reduce the brain damage in rats undergoing orthotopic liver transplantation,the mechanism may be related to down-regulating the expression of PKC and AQP4,and leptin can also improve long-term cognitive function after orthotopic liver transplantation in rats.