Effects of calcitriol and prednisolone on steroidogenic function in TM3 leydig cells

Purpose: This study aimed to investigate the effects of prednisolone and calcitriol on metabolic activity, steroidogenesis, and apoptosis-related markers in TM3 Leydig cells under human chorionic gonadotropin (hCG)-stimulated conditions.Materials and Methods: TM3 Leydig cells were divided into six groups: control, hCG, calcitriol, hCG + prednisolone, hCG + calcitriol, and hCG + prednisolone + calcitriol. CCK-8-based metabolic activity was evaluated using the CCK-8 assay. 3β-HSD and caspase-3 expression levels were examined immunocytochemically. Testosterone and INSL3 levels in the supernatant were measured by ELISA.Results: CCK-8-based metabolic activity increased in the hCG-treated group compared with the control group (116.88 ± 5.54% vs. 100.00 ± 6.80%). In contrast, metabolic activity decreased to 60.12 ± 5.53% in the calcitriol group, 45.02 ± 7.23% in the hCG + prednisolone group, 50.52 ± 2.97% in the hCG + calcitriol group, and 38.17 ± 3.54% in the triple-combination group. Total caspase-3-positive area was highest in the calcitriol-treated group (5.35 ± 1.38%). Testosterone levels were highest in the hCG + calcitriol group (34.39 ± 0.64 ng/mL). INSL3 levels increased from 41.02 ± 0.38 pg/mL in the control group to 50.28 ± 3.97 pg/mL in the calcitriol group, whereas they decreased to 35.57 ± 0.81 pg/mL in the hCG group and 35.06 ± 0.86 pg/mL in the triple-combination group.Conclusion: These findings suggest that the effects of calcitriol on Leydig cell responses may vary according to the conditions of administration, and that the suppressive effects of prednisolone may be modulated by accompanying stimuli.