Studies on the regulator of food intake in the neonatal chick

最近有报道称，用普乐普-L中枢给药可减少大鼠的摄食量。GLP-1的氨基酸序列在所有哺乳动物中都是相同的，鸡的GLP-1与哺乳动物的GLP-1具有很高的同源性。第一个实验的目的是阐明中枢注射哺乳动物和鸡的GLP-L是否抑制雏鸡的摄食量，并比较它们的效果。脑室注射哺乳动物和鸡的GLP-1强烈抑制雏鸡的摄食量。然而，两种GLP-1对食物摄入量的抑制作用是相似的。这些结果表明，具有多种氨基酸序列的GLP-1可能是鸡摄食量最强的抑制因子。第二个实验的目的是阐明中枢注射GLP-1所抑制的食物摄入量是否会被食欲刺激剂如禁食和神经肽Y(MN)所改变。饥饿6小时的鸟比饥饿3小时的鸟吃的食物要多得多，而不考虑…静脉注射NPY后10min，中枢注射NPY可显著增加大鼠的摄食量，而联合注射GIP-1(0.1、02或0.3IOTAg/10IOTA1)则呈剂量依赖性地减少摄食量。第三个实验的目的是阐明中枢注射GLP-1引起的摄食抑制是否通过激活下丘脑-垂体-肾上腺轴而起作用。首先，研究中枢应用促肾上腺皮质激素释放因子(CRF)对大鼠食物摄取的影响。随后观察了CRF和GLP-1对血浆皮质酮浓度的影响。CRF显著刺激皮质酮的释放，而GLP-I对血浆皮质酮浓度无明显影响。这些结果表明，CRF对雏鸡的摄食量有很强的抑制作用，但中枢GLP-1对摄食量的抑制可能不涉及下丘脑-垂体-肾上腺轴的激活。此外，在第四个实验中，GLP-1的C端氨基酸(7-36)对于中枢神经系统的生物活性具有重要的作用，特别是在第四个实验中，特别是在摄食行为方面，并且在第五个实验中，可能需要修改Exendin(9-39)的部分氨基酸序列来拮抗鸡的GLP-1受体

RecentIy, it was reported that centraI abministrati of GLP-l decreased food intake in rats. The amino acid sequences of GLP-1 are identical in all mammals, and chicken GLP-1 exhibits a high homology with mammalian GLP-1. The aim of first experiment was to elucidate whether central injection of mammalian or chicken GLP-l inhibits food intake in the chick, and to compare their effects. IntracerebroventricuIar administration of mammalian and chicken GLP-1 strongly inhibited food intake of chicks. However, the suppressive effect of both GLP-1 on food intake was similar. These results show that GLP-1 with a variety of amino acid sequences may be the most potent inhibitor of food intake in the chicken. The aim of second experiment was to elucidate whether suppressed food intake by central injection of GLP-1 would be modified by an appetite stimulant such as fasting and neuropeptide Y (MN). Birds starved for 6 h ate significantly more food than those starved for 3 h, while irrespective of the … More time for fasting GLP-1 strongly inhibited food intake as rapidly as 10 min after i.c.v injection., Central administration of NPY greatly enhanced food intake, but co-injection of GIP-1 (0.1,02 or 0.3 IOTAg/1O IOTA1) decreased food Intake in a dose-dependent fashion. The aim of third experiment was to elucidate whether the suppression of food intake induced by central injection of GLP-1 is mediated by activation of the hypothalamic-pituitary-adrenal axis. Fist, the effects of central administration of corticotropin-reIeasing factor (CRF) were investigated CRF strongly inhibited food intake. Thereafter, effects of central CRF or GLP-1 on plasma corticosterone concentration were examined CRF significantly stimulated corticosterone release, but GLP- I did not alter plasma corticosterone concentration These results suggest that CRF is a potent inhibitor of food intake in the chick, but the suppression of food intake induced by central GLP-1 may not involve the activation of hypothaIamic -pituitary-adrenal axis. Furthermore, it was dear that C-terminal amino acids of GLP-1(7-36) have an important role for the bioactivity in the central nervous system with special reference to feeding behavior in the fourth experiment and that modification of a part of ammo acid sequence of exendin (9-39) may be required to antagonize chicken GLP-1 receptor in fifth experiment Less