Studies on the regulator of food intake in the neonatal chick

最近，有报道称，中央给药glp - 1可以减少大鼠的食物摄入量。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具有高度的同源性。第一个实验的目的是阐明中央注射glp - 1是否抑制哺乳动物或鸡的食物摄入，并比较它们的效果。哺乳动物和鸡脑室注射GLP-1能显著抑制雏鸡的摄食量。然而，两种GLP-1对食物摄入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可能是鸡中最有效的食物摄入抑制剂。第二个实验的目的是阐明通过中枢注射GLP-1抑制食物摄入是否会被食欲刺激物如禁食和神经肽Y （MN）所改变。饥饿6小时的鸟比饥饿3小时的鸟吃了更多的食物，而与禁食时间无关，GLP-1在静脉注射后10分钟就强烈抑制了食物摄入。中央给药NPY可显著增加食物摄取量，但联合注射GIP-1（0.1、02或0.3 IOTAg/ 10iota1）可减少食物摄取量，且呈剂量依赖性。第三个实验的目的是阐明中枢注射GLP-1诱导的摄食抑制是否通过激活下丘脑-垂体-肾上腺轴介导。首先，研究了中央给药促肾上腺皮质激素释放因子（CRF）的作用，CRF能显著抑制食物摄入。随后，我们检测了中枢性CRF或GLP-1对血浆皮质酮浓度的影响，CRF显著刺激了皮质酮释放，而GLP-1没有改变血浆皮质酮浓度。这些结果表明，CRF是一种有效的食物摄入抑制剂，但中枢性GLP-1诱导的食物摄入抑制可能不涉及下丘脑-垂体-肾上腺轴的激活。此外，在实验4中，我们发现GLP-1的c端氨基酸（7-36）在中枢神经系统的生物活性中具有重要作用，特别是在饲养行为方面；在实验5中，我们发现可能需要修改部分扩展蛋白（9-39）的氨基酸序列来拮抗鸡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