Expression Levels of mRNA-Encoding PDGF Receptors in Goat Ovaries and the Influence of PDGF on the In Vitro Development of Caprine Pre-Antral Follicles

Contents The aims of this study were to investigate the expression levels of mRNA for platelet-derived growth factor (PDGF) receptors (PDGFR-alpha and -beta) in caprine follicles at different developmental stages and to evaluate the influence of PDGF on the in vitro development of pre-antral follicles. For this, goat primordial, primary and secondary follicles, as well as small (13 mm) and large (36 mm) antral follicles, were obtained, and PDGFR-alpha and -beta mRNA levels were quantified by real-time PCR. Furthermore, pre-antral follicles (>= 200 mu m) were isolated from goat ovaries and cultured for 18 days in alpha- minimum essential medium supplemented with PDGF at 50 or 100 ng/ml, containing or not FSH. Real-time PCR showed highest PDGFR-alpha mRNA levels in secondary follicles, while PDGFR-beta mRNA levels were highest in primary follicles onwards. Both receptors showed higher mRNA levels in granulosa/theca cells from small and large antral follicles than in their corresponding cumulusoocyte complexes. In culture, the percentage of antrum formation was significantly higher in 100 ng/ml PDGF compared with the same PDGF concentration associated with FSH. After 18 days, PDGF in both concentrations associated with FSH promoted follicular growth significantly higher than the control. Moreover, the addition of FSH to 50 ng/ml PDGF positively influenced the follicular growth when compared with the same PDGF concentration in the absence of FSH. In conclusion, PDGF is important for early goat folliculogenesis, because the presence of PDGFR-alpha and -beta mRNA was detected in all follicular categories, and PDGF associated with FSH stimulated the growth of goat pre-antral follicles isolated and cultured in vitro.