Hormones and binding proteins can regulate reproduction, but their involvement in sexual maturation remains to be elucidated. This study describes possible hormonal regulators of female sexual maturation. For this purpose, the release of steroid hormone progesterone (P4), insulin-like growth factor I (IGF-I) and IGF-binding proteins (IGFBP-3, IGFBP-4) were shown in this study. Sexual maturation in gilts was found to be associated with a significant increase in the release of P4, IGF-I and IGFBP-3 in vitro. Furthermore, sexual maturation was associated with significant increase in the expression of IGFBP-3 but not in IGFBP-4. The present data obtained from in vitro study indicate that sexual maturation in females is influenced by puberty-related changes in porcine ovarian signalling substances: increase in P4, IGF-I, IGFBP-3 but not IGFBP-4. It suggests that these signalling molecules could be potential regulators of porcine sexual maturation.
Sexual maturation, porcine granulosa cells, progesterone, insulin-like growth factor I and IGF-binding proteins