Effect Of α-MSH On Proliferation And Melanogenesis In Sheep Melanocytes

α-MSH is an important peptide hormone, which binds to MC1R to affect the production and distribution of melanin by cAMP pathway. The experiments are to study the influence of expression of hair related genes(MC1R,MITF,TYR), cAMP and cGMP content and melanin production to reveal the effects of a-MSH on melaninogenesis, by adding different doses of a-MSH in the medium of sheep melanocytes in vitro. The passage 7 sheep melanocytes were treated with different doses of a-MSH (0,0.1,1,10,100,1000 nmol/L) for 72 h. The main results were as follows:1 compared with the control group, the number of melanocytes with obvious dendrites in the experimental group showed obvious trend, adding 0.1-10 nmol/L cell numbers were on the rise,100-1000 nmol/L, the cell numbers decreased.2 qRT-PCR results showed that mRNA expression of MC1R, MITF and TYR gene expressions were the highest and were 1.878 fold changes (P<0.05),3.116 fold changes and 3.602 fold changes (P<0.01), respectively, in melanocytes with 10 nmol/L supplementary, compared with the control group. Along with the increase of the concentration, the expression of the genes showed a downward trend, but still higher than the control group.3 Western blot results showed that protein expression of MCIR, MITF, TYR and TYRP2 increased first and then reduced, were 1.687 fold changes,1.514 fold changes,1.386 fold changes and 1.265 fold changes(P<0.01), respectively, in melanocytes with 10 nmol/L supplementary, compared with the control group.4 ELISA method was used to detect the changes of cAMP and cGMP contents in the melanocytes. The results showed that total yield of cAMP was increased, and the total yield of cGMP was decreased, and the total amount of cAMP was 1.372 fold changes, and cGMP was 0.464 fold changes in in the melanocytes with 10 nmol/L supplementary, compared with that in the control group (P<0.01).5 Enzyme labeled method was used to detect the changes of melanin production. The results showed that the different doses of a-MSH can promote melanin production, with 2.551 fold changes was the highest in the melanocytes with 10 nmol/L supplementary, compared with that in the control group (P< 0.01), then decreased.Conclusion:the appropriate dose of a-MSH could promote the growth of sheep melanocyte dendrites, the number of cells and melanins production. a-MSH affects melanins production in melanocytes by regulating the cAMP pathway of melanogenesis with downstream of MC1R, MITF and TYR genes expression, and a-MSH of 10 nmol/L plays the most important roles in the phenotype and melanogenesis of melanocytes.