Expression of and in Hen Ovarian Follicles and Implication of Exogenous Leptin in Modulating Their mRNA Expression in In Vitro Cultured Granulosa Cells.

In this study, using a laying hen model, we determined the expression of and in different central and peripheral tissue and ovarian follicles at different stages of development. At the same time, mRNA expression of both genes in granulosa and theca cells harvested from follicles at different stages of folliculogenesis was also evaluated. Finally, we assessed the effect of leptin treatment on expression of and in in vitro cultured granulosa cells harvested from 1-5 mm to F3-F1 follicles. Our RT-qPCR results revealed that a comparatively higher expression of and was observed in ovary, hypothalamus, and pituitary. Abundant mRNA expression of was observed in small prehierarchical follicles (1-1.9 and 2-2.9 mm follicles; < 0.05), whereas mRNA expression of showed an increasing trend in large hierarchical follicles (F5-F1), and its abundant expression was observed in post-ovulatory follicles. mRNA expression was stable in granulosa cells harvested from 3-5 mm to F4 follicles, and exhibited a significantly higher expression in large hierarchical follicles. Conversely, relatively low mRNA expression of was observed in theca cells. mRNA expression was relatively lower in granulosa cells; however, theca cells exhibited a significantly higher mRNA expression of in F4 to F1 follicles. In the next experiment, we treated the in vitro cultured granulosa cells with different concentrations (1, 10, 100, and 1000 ng/mL) of exogenous leptin. Compared to the control group, a significant increase in the expression of was observed in groups treated with 1, 10, and 100 ng/mL leptin, whereas expression of was increased in all leptin-treated groups. When treated with 100 ng/mL leptin, and expression was upregulated in cultured granulosa cells harvested from both large hierarchical (F3-F1) and small prehierarchical follicles (1-5 mm). Based on these findings and evidence from mainstream literature, we envisage that and genes (in connection with hypothalamic-hypophysis axis) and leptin (via modulation of and expression) might have significant physiological roles, at least in part, in modulating the ovarian mechanisms, such as follicle development, selection, and steroidogenesis in laying hens.