Peripheral factors associated with early response in feeding to lysine-free diet in growing chickens

本项目的目的是确定哪些外周因素与不含赖氨酸日粮的鸡早期摄食量减少有关，以及哪些途径将这些因素的变化传递到中枢神经系统。试验日粮为纯净型-对照(赖氨酸)。HCL11.9g/kg)和不含赖氨酸(不含赖氨酸)。无赖氨酸日粮1小时后，血浆赖氨酸浓度开始下降至对照组的1/3，并持续下降至第4小时。除赖氨酸外，其他氨基酸均不随日粮赖氨酸水平变化。不含赖氨酸饲料的鸡的摄食量在5-6小时后开始减少。这一结果表明，血浆游离氨基酸浓度触发了饲喂无赖氨酸饲料的反应。在喂食不含赖氨酸的饲料后，梨状前皮质或下丘脑中的游离氨基酸浓度降低了一半，但皮质中也观察到了类似的变化。延髓Fos免疫组织化学染色显示，在给予饲料后3小时，不含赖氨酸组孤束核(NTS)的Fos免疫反应细胞数多于对照组。2小时后，去赖氨酸组伏隔核出现Fos免疫反应细胞。这些结果表明，血浆氨基酸浓度的外周信息是通过NTS和GOT传递到Ac的。综上所述，在通过NTS和GET传递到Ac的血浆赖氨酸浓度发生变化后，无赖氨酸日粮鸡的早期摄食量减少。

The objective of this project was to determine what peripheral factors were related to early reduction in food intake by chickens on lysine-free diet and which way conveyed the change of factors to the central nervous system.Three week-old male layer-type chickens were used. Experimental diets were purified-control (lysine. HCL11.9 g/kg) and lysine-free (no lysine. HCL) diets with same nitrogen and ME content.One hour after the lysine-free diet were presented, plasma concentration of lysine started to decrease to third of the control, and continued to decrease up to the fourth hours. Other amino acids than lysine did not change with dietary lysine level. Food intake by chickens on lysine-free diet started to decrease 5 or 6 hours after the diet was presented. This result suggests that plasma concentration of free amino acids triggered the response of feeding to lysine-free diet. Free amino acids concentration ini the pre-piriform cortex or hypothalamus, which was known to be involved in regulation of feeding, after feeding the lysine-free diet decreased half of the control, but similar changes were observed in the cortex. Therefore, tit is unlikely that amino acid in the brain did not relate to the response.Fos immunohistochemistry with medulla oblongata shows that the number of Fos immunoreactive cells observed at nucleus tractus solitarius(NTS) was larger in the lysine-free than control groups at three hours after presenting the diet. Two hours later Fos immunoreactive cells appeared at the nucleus accumbens (Ac) in the lysine-free group. These results suggest that peripheral information of plasma concentration of amino acid was conveyed thorough the NTS and got to the Ac.In conclusion, early reduction of food intake by chickens on lysine-free diet occurs after change in plasma concentration of lysine that is conveyed through the NTS and gets to the Ac.