Expression Of CART Protein In Sheep Ovarian Follicles And Functions On Folliclar Granulosa Cells In Vitro Culture

The development of sheep ovarian follicles is a complicated physiological process. There are many factors influencing its growth and atresia, such as follicle-stimulating hormone and insulin. In recent years, researchers found an endogenous neuropeptide named cocaine-and amphetamine-regulated transcript (CART). It can regulate mammals’ endocrine, metabolism, obesity and mental anxiety and as well as inhibit the function of bovine granulosa cells. Based on the previous researches, our test contains several aspects and main results are as follows:(1) Immunohistochemical localization of intrafollicular CART protein. The result indicated CART protein expressed in the big, middle and small follicles. We detected it in theca cells and granulose cells of adult sheep ovaries. But control groups had nonspecific reaction.(2) We obtained serum-free culture optimal culture system in vitro. The results indicated that groups treated with FSH and insulin showed a notable increment in stimulating granulosa cell proliferation and estradiol production. When concentration of insulin was10ng/mL, FSH5ng/mL, the number of granulosa cells was most, E2concentration in the medium was the highest (P<0.05), and culture system was optimal in this condition.(3) This study results showed the characteristics of some follicular granulosa cells congregated together, formed the embryonic stem cell-like masses, but we need further study to confirm whether had stem cell specificity or not.(4)CART plays a negative regulatory role for sheep granulosa cells function. When CART was0.1μM, the secretion of estradiol was lowest, extremely significant difference with control groups (P<0.01). CART can inhibit granulosa cells proliferation and estradiol secretion in sheep ovarian follicles. When concentration of CART continued rising to1μM, the secretion of estrogen increased than CART0.1μM, but has no significant difference.