?2 Adrenergic Receptor Mediates Tyrosine To Promote Melanin Formation In Duodenum Of Taihe Silk Fowl

In this work,(?2 adrenergic receptor)?2-AR,tyrosinase(TYR)and melanin in Taihe silky fowl were investigated by adding different concentrations of tyrosine in the diet,the concentrations of tyrosine were 0.38%,0.58%,0.78%,0.98%,1.18%,1.38%,1.58% and1.78% in the diet.The correlation among ?2-AR,tyrosinase and melanin was analyzed by comparing the relationship among ?2-AR,tyrosinase and melanin at day 15,day 29,day 43 and day 57 to elucidate the signaling pathway which mediated-molecular mechanism of melanogenesis in silky fowl about ?2-AR.The duodenum of silky fowl consisted of mucosa,submucosa,muscular layer and serous membrane by light microscopy.The melanin was located in the muscular layer.It suggested that melanin was not only in the skin,but also in the internal organs.DOPA staining showed that melanocytes existed in the lamina propria and crypt of silky fowl.By immunohistochemistry and immunofluorescence,the tyrosinase and ?2-AR in duodenum of silky fowl were detected,and the results showed that the ?2-AR was located in the intestinal glands,lamina propria,submucosal and intestinal villi of the duodenum.The tyrosinase was also present in the intestinal glands,lamina propria and intestinal villi of of the duodenum.Both of them were expressed in the same site.Feeding tyrosine can increase the number of ?2-AR positive cells and TYR positive cells.Silver staining showed that the distribution of argyrophil cells in the lamina propria and crypt,and the same with ?2-AR.?2-AR exist on the surface of argyrophil cells,synthesis of argyrophil cells can secrete a variety of substances mediated melanin,thus suggesting that ?2-AR can affect the argyrophil cells,so as to promote the synthesis of melanin.Feeding tyrosine can increase the number of argyrophil cells.The ?2-AR and tyrosinase and protein of the duodenum were tested by WB,respectively.With the increasing concentration of tyrosine in the diet,the expression of protein of ?2-AR and tyrosinase were increased.At the concentration of 1.18%,they reach the highest level.In conclusion,at a range of certain concentration,the tyrosine could promote the expression of the gene and protein of tyrosinase and ?2-AR.Moreover,melanin content was increaseing.These resultes suggested that ?2-AR signaling pathway could mediate the formation of melanin in Taihe silky fowl.