Effect of Vitamin D on basal and Luteinizing Hormone (LH) induced testosterone production and mitochondrial dehydrogenase activity in cultured Leydig cells from immature and mature rams

The objectives of this study were to investigate the potential effects of 1α,25-(OH)2VD3 (biologically active form of Vitamin D) on basal and LH-induced testosterone production and mitochondrial dehydrogenase activity in Leydig cells from immature and mature rams cultured in vitro. Leydig cells were isolated from testes of immature and mature rams, treated without (control) or with increasing concentrations of LH (1, 10, 100 ng/ml) and/or 1α,25-(OH)2VD3 (1, 10, 100 nM). After 24 h, concentrations of testosterone in culture media were measured. After 96 h, mitochondrial dehydrogenase activity in Leydig cells were measured. In immature and mature ram Leydig cells, treatment with 10 and 100 ng/ml LH increased testosterone production and mitochondrial dehydrogenase activity. Treatment with 1α,25-(OH)2VD3 in the absence of LH did not increase testosterone production, but 10 and 100 nM 1α,25-(OH)2VD3 increased LH induced testosterone production for both immature and mature ram Leydig cells. Treatment with all doses of 1α,25-(OH)2VD3 in the absence of LH and 10 and 100 ng/ml LH in the absence of 1α,25-(OH)2VD3 increased mitochondrial dehydrogenase activity for cultured Leydig cells from immature and mature rams and 1 and 10 nM 1α,25-(OH)2VD3 treatment enhanced the LH induced increase in mitochondrial dehydrogenase activity. Result demonstrate Vitamin D3 induced regulation of function of Leydig cells from immature and mature rams cultured in the presence or absence of LH and support a potential role for Vitamin D3 in regulation of gonadal function in rams.