Efeito da Proteína Morfogenética Óssea 15 (BMP-15) e do Hormônio Folículo Estimulante (FSH) sobre o desenvolvimento de folículos ovarianos bovinos

Abstract

This study aims to 1) evaluate the effect of BMP-15 and FSH, alone or in different combinations on the in vitro development, survival and antrum formation of bovine secondary follicles and 2) quantify the levels of mRNA expression for BMP-15 receptors (BMPR-IB and BMPR-II), FSH receptor and Kit Ligand in follicles grown in vivo and in vitro. With regard to culture, secondary follicles were microdissected and cultured for twelve days in α-MEM+ alone, or supplemented with BMP-15 and/or FSH, alone or in various associations. After culture, follicular diameter were evaluated, viability and rate of antrum formation. For the analyzes gene expression, by real time PCR, were used follicles cultured in the different treatments for comparisons of the levels of mRNA. After the culture period it was found that the association of BMP+FSH (0-12) stimulated a significant increase in follicular diameter in relation to other treatments (p<0.05), as well as stimulated the formation of antral cavity more effectively the control (MEM) and BMP-15 alone (p<0.05). However, for survival, after 12 days treatment BMP+FSH (0-12) significantly reduced follicular viability when compared to other treatments (p<0.05). The results showed that the levels of mRNA for BMP receptor type I (BMPR-IB) were significantly higher in follicles cultured with MEM when compared to other treatments, while levels of mRNA for the receptor type II (BMPR-II) did not differ between treatments. The highest levels of mRNA for the FSH receptor were detected in follicles cultured with BMP-15 alone. In conclusion, this study demonstrated that combination of BMP-15+FSH (D0-D12) accelerates the growth of bovine preantral follicles cultured for 12 days, but this effect reduces the follicular viability, affecting the ultrastructural integrity of the follicles. Furthermore, the addition of BMP alone increased expression levels of RNAm for FSHR after 12 days of culture , showing that BMP-15 and FSH may contribute significantly to the in vitro development of preantral follicles cultured for 12 days in this specie.