膳食变化对大鼠下丘脑 AgRP 表达的影响

摘要

目的：分析膳食变化对大鼠下丘脑刺鼠相关蛋白（ AgRP）表达的影响，探讨AgRP在肥胖发生中的作用，为肥胖的研究提供一个新的思路。方法将80只体重为100～120 g的雄性Wistar大鼠随机分成高能饲料组（ n＝40）、饥饿组（ n ＝20）、对照组（ n ＝20）。高能组给予自制的高能饲料，对照组和饥饿组给予基础大鼠饲料。12周后，高能组体重超过对照组平均体重30％的大鼠设为膳食诱导肥胖（ DIO）组，饥饿组给予72 h禁食，自由饮水。取大鼠下丘脑采用免疫组化实验和western blot检测AgRP表达。结果免疫组化显示DIO组大鼠和饥饿组大鼠下丘脑AgRP表达显著高于对照组（ P ＜0滗．05）；而DIO组大鼠和饥饿组下丘脑AgRP表达差异无统计学意义（ P ＞0．05）。Western Blot实验显示DIO组和饥饿组大鼠下丘脑AgRP表达明显高于对照组大鼠（ P ＜0．01）。而DIO组大鼠和饥饿组大鼠下丘脑AgRP表达差异无统计学意义（ P ＞0．01）。结论长期高能饮食导致肥胖，其下丘脑内AgRP表达的增高可能是导致机体摄食量和体重增加并引起肥胖的主要因素之一。饥饿状态下，下丘脑内AgRP表达增高，可能是由于在饥饿状态下机体内瘦素、胰岛素、糖的减少共同所致。%Objective To observe the effect of dietary change on the expression of AgRP in hypothalamus of rats,and to explore the action mechanism of AgRP in pathogenesis of obesity.Methods Eighty male Wistar rats weighted 100~120g were randomly divided into high-energy diet group ( n =40),hunger group ( n =20),control group ( n =20).The rats in high-energy diet group were given self-made high-energy food,the rats in control group and hunger group were fed with basal food.After 12 weeks, the rats in high-energy diet group whose weight exceeded30 % of mean weight in control group were regarded as diet-induced obesity group ( DIO group) ,however,the rats in hungry group were fasted for 72h,free to drink in the meantime.Then the expression levels of AgRP were detected by immunohistochemistry (IHC) and Western Blotting for all the rats.Results The results by IHC showed that the expression levels of AgRP in hypothalamus of rats in DIO group (5531.10 ±330.40) and hungry group (49016.7 ±410 2.4 ) were significantly higher than those in control group(919.62 ±325.98) ( P <0.01),however,there were no significant differences between DIO group and hungry group ( P >0.05).The results by Western blotting showed that the expression levels of AgRP in hypothalamic of rats in DIO group(0.99 ±0.01) and hungry group(0.87 ±0.02) were significantly higher than those in control group(0.67 ±0.01) ( P <0.01),but there were no significant differences between DIO group and hungry group ( P >0.05).Conclusion Long-term high-energy diet can result in obesity,and the overexpression of AgRP in hypothalamus may be one of the main factors which can lead to the increase of food intake,weight gain and obesity.During starvation condition, the increase of AgRP expression in hypothalamus may be caused by the common effects of the reduction of leptin,insulin and sugar within organism.