Effect of 1α,25-dihydroxyvitamin D3 on progesterone secretion by porcine ovarian granulosa cells

The essential role of vitamin D (VD) in bone metabolism and mineral homeostasis is well established knowledge. Research indicates that classical and non-classical pathways of VD affect also cell proliferation and differentiation, the immune system, infection, and cancer. VD receptor (VDR) and VD metabolizing enzymes have been detected in female reproductive tissues, such as ovary, uterus and placenta. The presence of VD metabolites was demonstrated in follicular fluid (FF) in women undergoing in vitro fertilization and embryo transfer (IVF-ET). The recent studies show that VD regulates the expression of a large number of genes in reproductive tissues implicating a role for VD in female reproduction and pregnancy outcomes. There is increasing human and animal data suggesting that VD status may be associated with impaired fertility, endometriosis, polycystic ovary syndrome (PCOS), and ovarian cancer. The presence of VDR in both animal and human ovarian tissue has raised the question of a possible direct role for 1α,25-dihydroxyvitamin D [1α,25(OH)2D3] in the regulation of steroid hormone synthesis and secretion. Our recent data have demonstrated that 1α,25(OH)2D3 may affect in vitro insulin- and follicle-stimulating hormone (FSH)-induced progesterone secretion by porcine ovarian granulosa cells. The molecular mechanisms of this action should be further investigated.