蛋鸡和肉鸡下丘脑中生长抑素神经原分布的比较研究

应用免疫组织化学技术显示蛋鸡和肉鸡生长发育过程中下丘脑生长抑素（SS）免疫阳性神经原的分布。研究结果表明两种鸡下丘脑中SS神经原的分布相似，均分布在下丘脑外侧和腹内侧核。下丘脑外侧和腹内侧核的SS神经原可分为两群：中间群和外侧群。通过计数中间群中SS神经原数量发现两种鸡SS神经原数量在生长发育中变化不同。肉鸡在第3周时SS神经原数量最多，于第6周显著减少（P＜0.01)，然后一直维持到第9周。蛋鸡SS神经原数量在第3周时稍增加后于第6周暂时降低（P＜0.05)，然后在第9周时明显增加（P＜0.05)。在发育过程中，肉鸡SS神经原数量的变化比蛋鸡大。尽管肉鸡和蛋鸡SS神经原数量没有明显的性别变化，但公鸡SS神经原的总数比母鸡要高。本实验结果表明蛋鸡和肉鸡下丘脑中SS神经原数量与血浆中GH水平呈负相关，下丘脑中SS神经原数量可以解释蛋鸡和肉鸡血浆中GH水平的差异。

A Comparative Study of the Distribution of Somatostatin-immunoreactive Neurons in the Hypothalamus of Layer and Broiler Chickens

Immunohistochemical method was used to investigate the distribution of somatostatin-immune positive neuron (SS-neuron) in the hypothalamus of layer and broiler chickens during growth.Our results showed that the topographical location of SS-neuron displayed a similar pattern in both broiler and layer chickens.The group of SS-neuron was observed in the lateral hypothalamus and ventromedial nuclei.The SS-neuron in the lateral hypothalamus might be divided into two group:medial area and lateral area.When the data from different ages and sexes were pooled,the total number of SS-neuron in the medial area of the lateral hypothalamus was significantly higher (P<0.05) in broilers than in layers before 9 weeks of age.The strain difference was most evident at 6 weeks of age (P<0.01).The ontogeny of SS-neuron number exhibited a different pattern between broilers and layers.The broilers at the age of 3 weeks showed the maximal number of SS-neuron which decreased significantly (P<0.01) at the age of 6 weeks and then maintained a similar level until at the age of 9 weeks.In layer chickens,after a slight increase in the number of SS-neuron at the age of 3 weeks,the number temporarily fell (P<0.05) at the age of 6 weeks,and then increased significantly (P<0.05) at the age of 9 weeks.The variation in the number of SS-neuron was greater in broilers than in layers during development.Though no obvious sex difference was identified in the distribution of the SS-neuron both in the broiler and layer,the total number of SS-neuron in the male was higher than that in the female.Our results show that the age-related changes in the number of SS-neuron corresponds with the changes in GH plasma concentration in the chicken and the SS-IPN in the hypothalamus could be responsible for the difference of GH concentration between two strains of chickens.