β2-肾上腺素受体（β2-AR）信号通路介导酪氨酸促乌骨鸡黑色素生成的研究

The black-bone silky fowl is generally accepted as an international standard specie of silky chicken with nutrition and drug value because of melanin. However, the mechanisms of melanogenesis are unknown. This project will be conducted to investigate the mechanisms of tyrosine (Tyr) activate Tyrosinase (TYR) and hyperpigmentation in Taihe black-bone silky fowl. The chickens will be fed with different levels of Tyr ration for studying the metabolic patterns of Tyr, quantitating the dopaminergic cells and claritying correlations with catecholamine levels and melanin synthesis. In addition, the pathways of catecholamines utilization and the synthesis of melanin in melanocytes will be determined. The melanocytes of silky fowl will be cultured in vitro with different levels of epinephrine or the blocking agent/activator correlative factors of cellular signal to illustrate the E-β2AR-Gs-AC-cAMP-PKA cellular signal transduction pathway of melanin synthesis. Furthermore, TYR gene / protein expression, melanocytes and melanin will be analyzed by in vivo and in vitro experiments. In conclusion, this project is aimed to reveal the mechanisms of Tyr was utilized efficiently to synthesize abundant melanin in Taihe black-bone silky fowl. Furthermore, the Taihe black-bone silky fowl with more melanin and value are breed by regulating the signal pathway.

乌骨鸡具有丰富的营养价值和药效作用，其发挥药效的主要物质基础是黑色素，但乌骨鸡黑色素生成的机理尚未阐明。本项目通过动物试验，在饲粮中添加不同水平酪氨酸，鉴定泰和乌骨鸡体内参与酪氨酸代谢和黑色素生成的相关细胞类型；检测儿茶酚胺和黑色素沉积水平；黑色素生成关键酶基因和蛋白表达水平，阐明儿茶酚胺与黑色素生成的关系。采用体外培养黑色素细胞，培养液中添加不同浓度肾上腺素的方法，鉴定黑色素细胞肾上腺素受体和相关信号因子及对黑色素生成的影响，阐明儿茶酚胺可通过E-β2AR-Gs-AC-cAMP-PKA信号转导通路，提高酪氨酸酶基因表达和/或酶活性，影响黑色素的生成。通过本研究，可揭示β2AR介导黑色素生成的信号通路，为黑色素生成机理研究提供新思路；也为生产中，通过调控黑色素生成信号通路的方法，养殖出黑色素沉积更多、药效作用更强的商品乌骨鸡提供参考。

泰和乌骨鸡是一种含有丰富黑色素的特色经济动物，且其药用价值与黑色素相关，但目前乌骨鸡体内黑色素生成的详细机理仍然没有完全阐明。本项目通过在饲料中添加不同浓度的酪氨酸，检测乌骨鸡十二指肠管壁内的黑色素分布位置和含量；黑色素生成限速酶—酪氨酸酶（TYR）和β2肾上腺素受体（β2-AR）的分布位置及两者的位置关系；TYR和β2-AR mRNA和蛋白的表达量。结果表明，在0-1.38%的浓度范围内，酪氨酸可促进TYR与β2-AR基因和蛋白的表达，且促进十二指肠TYR活性和黑色素沉积量增加。0-1.38%浓度范围内，酪氨酸、TYR与β2-AR基因与蛋白，及其黑色素生成量呈正相关。试验结果提示，β2-AR介导酪氨酸调控TYR基因表达影响黑色素的生成。本项目也可在实际生产中，通过改变饲料中酪氨酸浓度来调控乌骨鸡黑色素的生成，为提高乌骨鸡的药用价值提供参考依据。