Covasa M, Ritter R C
Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman 99164-6520, USA.
Peptides. 1998;19(8):1407-15. doi: 10.1016/s0196-9781(98)00096-5.
Rats maintained on high-fat diets often exhibit increased food intake and weight gain. We hypothesized that high-fat diets might result in reduced sensitivity to hormonal signals responsible for terminating food intake--satiety signals. The intestinal hormone cholecystokinin (CCK) and the gastrointestinal neuropeptide, bombesin (BBS) both have been proposed as satiety signals. To determine whether maintenance on high-fat diets alters sensitivity to satiating effects of CCK and bombesin (BBS), rats were maintained on a low fat diet (LF), a high-fat diet that was isocaloric with the low-fat diet (HF), or one of two hypercaloric high-fat diets (HF-1, HF-2) that differed from HF and LF in fat, fiber, and total caloric content. CCK and bombesin reduced food intake significantly less in rats maintained on high-fat diets, compared to those on the low fat diet. Neither high caloric intake, which was associated with increased body weight gain on the two hypercaloric diets, nor fiber content of the diet accounted for the reduced response of HF rats to CCK. Rather, reduced sensitivity to CCK was related only to the high proportion of calories taken as fat. We also determined whether reduced CCK sensitivity was due to the maintenance on a particular diet or to the diet eaten during a CCK test. After CCK, rats maintained on LF reduced food intake more (49%) than rats maintained on HF (22%), regardless of whether they ate HF or LF during the CCK test itself. These findings indicate that maintenance of rats on high-fat diets reduces sensitivity to some peptide satiety signals. Reduced sensitivity to satiety signals might contribute to overeating and obesity often observed when rats are maintained on high-fat diets.
长期食用高脂饮食的大鼠通常会出现食物摄入量增加和体重增加的情况。我们推测，高脂饮食可能会导致对负责终止食物摄入的激素信号（即饱腹感信号）的敏感性降低。肠促胰酶肽（CCK）和胃肠神经肽蛙皮素（BBS）均被认为是饱腹感信号。为了确定高脂饮食是否会改变对CCK和蛙皮素（BBS）饱腹感作用的敏感性，将大鼠分别饲养在低脂饮食（LF）、与低脂饮食热量相等的高脂饮食（HF）或两种高热量高脂饮食（HF-1、HF-2）中，这两种高热量高脂饮食在脂肪、纤维和总热量含量方面与HF和LF有所不同。与低脂饮食组的大鼠相比，高脂饮食组的大鼠中CCK和蛙皮素对食物摄入量的显著降低作用更小。在两种高热量饮食中，高热量摄入（与体重增加相关）和饮食中的纤维含量均不能解释HF组大鼠对CCK反应降低的原因。相反，对CCK敏感性降低仅与以脂肪形式摄入的高热量比例有关。我们还确定了CCK敏感性降低是由于长期食用特定饮食还是由于CCK测试期间所吃的饮食所致。注射CCK后，无论在CCK测试期间它们吃的是HF还是LF，LF组饲养的大鼠比HF组饲养的大鼠减少的食物摄入量更多（49%对22%）。这些发现表明，长期给大鼠喂食高脂饮食会降低对某些肽类饱腹感信号的敏感性。对饱腹感信号敏感性降低可能导致大鼠长期食用高脂饮食时经常出现的暴饮暴食和肥胖。
