Effects of transforming growth factor β1 on steroidogenesis of feline granulosa cells cultured .

Context: Little is known about the hormonal regulation of feline ovarian granulosa cell proliferation and steroidogenesis.

Aims: To determine if transforming growth factor β1 (TGFB1), activin, epidermal growth factor (EGF), follicle stimulating hormone (FSH), luteinizing hormone (LH), melatonin, and insulin-like growth factor 1 (IGF1) regulate granulosa cell steroidogenesis and proliferation in cats, three experiments were conducted in winter season.

Methods: Granulosa cells were isolated and treated in vitro with various hormones in serum-free medium for 48h after an initial 48h plating in 10% fetal calf serum.

Key Results: Treatment with IGF1 and FSH increased (P <0.05) estradiol production by 2.3- and 1.33-fold, respectively. In contrast, TGFB1 blocked (P <0.05) IGF1-induced estradiol production and inhibited FSH-induced estradiol production by 60%. Combined with FSH or FSH plus IGF1, TGFB1 inhibited (P <0.05) cell proliferation, whereas TGFB1 increased progesterone production by 2.8-fold in the presence of FSH plus IGF1. EGF decreased (P <0.05) FSH plus IGF1-induced estradiol production by 89% but did not affect progesterone production or cell numbers. Activin did not affect (P >0.10) cell numbers or steroidogenesis in the presence of FSH plus IGF1. Melatonin and LH decreased (P <0.05) estradiol production 53% and 59%, respectively, without affecting progesterone production or cell proliferation.

Conclusions: The present study has identified TGFB1 as a major regulator of feline ovarian function, in addition to EGF, IGF1, melatonin, LH and FSH.

Implications: These studies will provide useful information for future development of fertility control in feline species.