Comparative role of retinol, retinoic acid and β-carotene on progesterone secretion by pig corpus luteum in vitro

Abstract

Quadruplicate wells of pig luteal cells were incubated for 24 h in the presence of different concentrations of retinol, β-carotene (0, 1 x 10-5, 1 x 10-6 and 1 x 10-7 M) or retinoic acid (0, 1 x 10-6, 1 x 10-7 and 1 x 10-8 M). In addition, the responsiveness of luteal cells to LH challenge was also evaluated. Progesterone was assayed in the media. Cell viability was estimated using trypan blue exclusion and showed over 95% viability. In the presence of LH, progesterone content in the medium was increased by 7-fold. As compared to their respective controls, all concentrations of retinoic acid and β-carotene increased progesterone content in the media. The highest level of stimulation was observed with 1 x 10-6 M-retinoic acid (5-fold increase) and 1 x 10-7 M-β-carotene (10-fold increase). Only 1 x 10-5 M-retinol stimulated progesterone secretion (over 3-fold). Therefore, retinol, retinoic acid and β-carotene stimulate progesterone secretion by pig luteal cells in vitro.