Abstract
Gossypol is a yellowish polyphenolic aldehyde found in the pigment glands of the cotton plant. Cottonseed and cottonseed meal (CSM) are popular concentrates for both beef and dairy cattle in cotton growing countries especially in South East Asia. Gossypol, however, is known to inhibit steroidogenesis and the reproductive system in cows; gossypol inhibits estradiol (E2) and progesterone (P4) production in bovine granulosa cells. However, the effect of gossypol on bovine theca cell steroidogenesis has not been clarified yet. The aim of this study was to investigate the effect of gossypol on bovine theca cell steroidogenesis. Theca cells were isolated from preovulatory follicles (10–15mm diameter with clear follicular fluid and healthy appearance) and were cultured for 24h in the presence or absence of LH (1ng/ml) together with graded doses of gossypol (0–25µg/ml). Androstenedione (A4) and P4 in the medium were measured by enzyme-linked immunosorbent assay (ELISA). Total RNA was extracted and mRNA expression was measured by real-time PCR. LH increased production of androstenedione and progesterone. Gossypol inhibited LH-stimulated A4 production in dose-dependent manner, but had no apparent effect on LH-stimulated P4 production by cultured theca cells. LH increased the mRNA levels of CYP17, HSD3B1, CYP11A1, StAR and LHR. Gossypol decreased the levels of mRNA of all steroidogenic enzymes examined and StAR but not LHR. These results indicate that gossypol inhibits theca cell androgen production by down regulating mRNA expression of the factors involved in steroid production of bovine theca cells.
