Bone Morphogenetic Protein‐6 (BMP‐6) Stimulates the Antrum Formation by the Regulation of its Signalling Pathway in Caprine Pre‐antral Follicles Cultured In Vitro

Abstract

BMP-6 has been found to be important to ovarian cells and oocyte, as well as to uterus. Thus, this study investigated the effect of bone morphogenetic protein (BMP-6) and recombinant follicle-stimulating hormone (rFSH) alone or in combination on the in vitro culture (IVC) of isolated caprine secondary follicles (Experiment 1) and the mRNA levels for BMP receptors/Smad signalling pathway (BMPR1A, BMPR2, SMAD1, SMAD4, SMAD5, SMAD6, SMAD7 and SMAD8) in vivo and in vitro using BMP-6 (Experiment 2). Secondary follicles were cultured in αMEM(+) alone (control medium) or supplemented with BMP-6 at 1 or 10 ng/ml and rFSH alone or the combination of both BMP-6 concentrations and rFSH. The results from Experiment 1 showed that the antrum formation rate was higher in the BMP-6 at 1 ng/ml (p < 0.05) than in MEM. In Experiment 2, the mRNA expression for BMPR2, SMAD1, SMAD5 and SMAD6 was detected in non-cultured control and after in vitro culture (MEM and 1 ng/ml BMP-6); while the expression of SMAD7 and SMAD8 mRNA was only detected after IVC, SMAD4 was only detected in the BMP-6 at 1 ng/ml treatment. In conclusion, the low BMP-6 concentration positively influenced antrum formation and ensured normal mRNA expression for BMP receptor and Smads after IVC of caprine secondary follicles.

Increased bone morphogenetic protein-6 in follicular fluid and granulosa cells may correlate with fertilization and embryo quality in humans

“…Conversely, mutations in the BMP-15 gene are associated with infertility in sheep and premature ovarian failure in humans (32,33). Other studies have demonstrated that BMP-6 is associated with follicle growth in the pre-antral and antral stages (34,35). In addition, some studies have demonstrated that BMP-15 and GDF-9 are able to stimulate granulosa cell mitosis in pre-antral follicles (12,31,36).…”

The FSH–mTOR–CNP signaling axis initiates follicular antrum formation by regulating tight junction, ion pumps, and aquaporins

“…However, the studies on iFFA are lagged behind. For example, the latest review on iFFA was published in 2010 ( 18 ), and only handful research articles on iFFA could be retrieved from the PubMed database ( 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ). In addition, the research targets are relative narrow.…”