瘦素对下丘脑腹内侧核损伤性肥胖大鼠的代谢影响

目的 :　探讨外周输注瘦素对下丘脑腹内侧核 (ventromedial hypothalamus,VMH)损伤性肥胖大鼠的代谢影响。方法 :　大鼠分成四组 ,分别是 (1 ) VMH损伤 +瘦素 ,(2 ) VMH损伤 +生理盐水 ,(3 ) VMH伪损伤 +瘦素 ,(4 ) VMH伪损伤 +生理盐水。在 VMH损伤或伪损伤后 ,在背部植入灌注瘦素或生理盐水的微泵 ,每天记录体重、摄食量。 7d后 ,留取血样测定血浆葡萄糖、甘油三酯、总胆固醇、胰岛素及瘦素 ;分离子宫外周脂肪垫 (perimetric fat pad,PFD)并称重 ;留取胰腺组织测定胰岛细胞增殖细胞核抗原 (proliferating cell nuclear antigen,PCNA)。结果 :　在VMH损伤的两组中 ,瘦素和生理盐水输注的大鼠体重增加和摄食量没有差别 ,但在 VMH伪损伤两组中 ,瘦素输注组的体重增加和摄食量少于生理盐水输注组。瘦素输注的 VMH损伤和伪损伤组的血浆胰岛素、甘油三酯、总胆固醇分别低于其相应的生理盐水对照组。瘦素输注的 VMH损伤和伪损伤两组的血浆瘦素水平没有差别 ,而在 VMH伪损伤的两组中 ,瘦素输注组的瘦素水平高于其输注生理盐水的对照组。在 VMH损伤的两组中 ,瘦素和生理盐水输注的肥胖大鼠 PFD没有差别 ;在 VMH伪损伤的两组中 ,瘦素输注组的 PFD少于生理盐水输注组。在 VMH损伤组中 ,瘦素输注组的 PCNA阳性率明

EFFECTS OF PERIPHERAL INFUSION OF LEPTIN ON METABOLISM IN VENTROMEDIAL HYPOTHALAMUS-LESIONED OBESE RATS

Objective: To investigate the effects of peripheral leptin infusion on metabolism in ventromedial hypothalamus (VMH) lesioned obese rats. Methods: Four groups were prepared: (1) VMH lesioned rats with infusion of leptin, (2) VMH lesioned rats with infusion of saline, (3) sham VMH lesioned rats with infusion of leptin and (4) sham VMH lesioned rats with infusion of saline. After VMH lesion and sham operations, a mini pump filled with either leptin or saline was implanted into the back of rats. Body weight and food intake were recorded daily. Seven days later, all rats were sacrificed after overnight fast. Blood samples were collected for determination of glucose, triglyceride, total cholesterol, insulin and leptin. Perimetric fat pad (PFD) was isolated and weighed. Pancreas was embedded by paraffin and sectioned, and performed by immunostaining with proliferating cell nuclear antigen (PCNA) for study of the proliferative activity of insular cells. Results: In sham operated groups, food intake and increased body weight decreased significantly in rats with leptin infusion than those without leptin infusion. No similar findings were observed in VMH lesioned rats. Plasma insulin, triglyceride and total cholesterol in the rats with leptin infusion regardless of VMH lesion or sham operations were decreased when compared with their controls. In respect to PFD, two VMH lesioned groups did not differ, but two sham operated groups differed. Positive PCNA rate in VMH lesioned rats receiving leptin declined significantly. Conclusion: Leptin regulations of food intake, body weight and body fat are dependent upon intact VMH. Peripheral infusion of leptin decreases plasma triglyceride and total cholesterol in VMH lesioned rats.