Immunolocalization for glucocorticoid receptor and effect of cortisol on in vitro development of preantral follicles.

The aim of this study was to evaluate the immunolocalization for glucocorticoid receptor (NR3C1) in goat ovarian follicles and the effect of cortisol on in vitro development of preantral follicles. Goat ovarian fragments were cultured for 7 days under different cortisol concentrations (0, 1, 5 and 10 ng/ml). Before and after culture, the protein expression of NR3C1 was analyzed in ovarian tissue by immunohistochemical analysis. Moreover, the endpoints follicular morphology, viability, activation as well as follicular and oocyte diameter were also analyzed. The NR3C1 was strongly expressed in oocytes of primordial and antral follicles. A progressive increase of immunostaining for NR3C1 in granulosa cells from primordial to antral follicles was observed regardless of the treatment. After in vitro culture, it was observed a significant reduction in the rate of normal preantral follicles rate in the 10 ng/ml cortisol treatment when compared to the other treatments. Moreover, follicular and oocyte diameter significantly decreased in all treatments (cortisol 0, 1, 5 and 10 ng/ml) compared to the fresh control. After culture, the activation rate significantly increased when the follicles were exposed to 1, 5 and 10 ng/ml cortisol compared to the fresh control. In conclusion, it was observed the presence of NR3C1 in the oocyte and granulosa cells in all follicular categories, except in granulosa cells of primordial follicles. The in vitro culture showed that high cortisol concentration (10 ng/ml) exerts a deleterious effect on follicular survival.

Gene Expression During Early Folliculogenesis in Goats Using Microarray Analysis.

Understanding of gene expression and metabolic, biological and physiological pathways in ovarian follicular development can have a significant impact on the dynamics of follicular atresia or survival. In fact, some oocyte loss occurs during the transition from secondary to early tertiary follicles. This study aimed to understand, by microarray analysis, the temporal changes in transcriptional profiles of secondary and early antral (tertiary) follicles in caprine ovaries. Ovarian follicles were microdissected and pooled to extract total RNA. The RNA was cross hybridized with the bovine array. Among 23,987 bovine genes, a total of 14,323 genes were hybridized with goat mRNAs while 9,664 genes were not. Of all the hybridized genes, 2,466 were stage-specific, up- and down-regulated in the transition from secondary to early tertiary follicles. Gene expression profiles showed that three major metabolic pathways (lipid metabolism, cell death, and hematological system) were significantly differentiated between the two follicle stages. In conclusion, this study has identified important genes and pathways which may potentially be involved in the transition from secondary to early tertiary follicles in goats.