Bernier N J, Peter R E
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
Neuroendocrinology. 2001 Apr;73(4):248-60. doi: 10.1159/000054642.
Fish urotensin I (UI), a member of the corticotropin-releasing hormone (CRH) family of peptides, is a potent inhibitor of food intake in mammals, yet the role of UI in the control of food intake in fish is not known. Therefore, to determine the acute effects of UI on appetite relative to those of CRH, goldfish were given intracerebroventricular (i.c.v.) injections of carp/goldfish UI and rat/human CRH (0.2-200 ng/g) and food intake was assessed for a 2-hour period after the injection. UI and CRH both suppressed food intake in a dose-related manner and UI (ED50 = 3.8 ng/g) was significantly more potent than CRH (ED50 = 43.1 ng/g). Pretreatment with the CRH receptor antagonist, alpha-helical CRH(9-41), reversed the reduction in food intake induced by i.c.v. UI and CRH. To assess whether endogenous UI and CRH modulate fish appetite, goldfish were given intraperitoneal implants of the glucocorticoid receptor antagonist, RU-486 (50 and 100 microg/g), or the cortisol synthesis inhibitor, metyrapone (100 and 200 microg/g), and food intake was monitored over the following 72 h. Fish treated with either RU-486 or metyrapone were characterized by a sustained and dose-dependent reduction in food intake. Pretreatment with i.c.v. implants of alpha-helical CRH(9-41) partially reversed the appetite-suppressing effects of RU-486 and metyrapone. In a parallel experiment, the effects of RU-486 (100 microg/g) and metyrapone (200 microg/g) intraperitoneal implants on brain UI and CRH gene expression were assessed. Relative to sham-implanted controls, fish treated with RU-486 or metyrapone had elevated UI mRNA levels in the hypothalamus and CRH mRNA levels in the telencephalon-preoptic brain region. Together, these results suggest that UI is a potent anorectic peptide in the brain of goldfish and that endogenous CRH-related peptides can play a physiological role in the control of fish appetite.
鱼尿紧张素I（UI）是促肾上腺皮质激素释放激素（CRH）肽家族的成员之一，是哺乳动物食物摄入的有效抑制剂，但UI在鱼类食物摄入控制中的作用尚不清楚。因此，为了确定UI相对于CRH对食欲的急性影响，给金鱼脑室内（i.c.v.）注射鲤鱼/金鱼UI和大鼠/人类CRH（0.2 - 200 ng/g），并在注射后2小时评估食物摄入量。UI和CRH均以剂量相关的方式抑制食物摄入，且UI（半数有效剂量ED50 = 3.8 ng/g）比CRH（ED50 = 43.1 ng/g）的效力显著更强。用CRH受体拮抗剂α - 螺旋CRH(9 - 41)预处理可逆转i.c.v.注射UI和CRH引起的食物摄入量减少。为了评估内源性UI和CRH是否调节鱼类食欲，给金鱼腹腔植入糖皮质激素受体拮抗剂RU - 486（50和100 μg/g）或皮质醇合成抑制剂甲吡酮（100和200 μg/g），并在接下来的72小时监测食物摄入量。用RU - 486或甲吡酮处理的鱼的特征是食物摄入量持续且剂量依赖性减少。用α - 螺旋CRH(9 - 41)的i.c.v.植入物预处理可部分逆转RU - 486和甲吡酮的食欲抑制作用。在一项平行实验中，评估了RU - 486（100 μg/g）和甲吡酮（200 μg/g）腹腔植入对脑UI和CRH基因表达的影响。相对于假植入对照，用RU - 486或甲吡酮处理的鱼下丘脑UI mRNA水平升高，端脑 - 视前脑区域CRH mRNA水平升高。总之，这些结果表明UI是金鱼脑中一种有效的食欲抑制肽，并且内源性CRH相关肽在鱼类食欲控制中可发挥生理作用。
