Luteinization of bovine granulosa cells and corpus luteum formation associated with loss of androgen-aromatizing ability

Abstract

The relative aromatizing ability of bovine luteinizing granulosa cells and dispersed luteal cells in tissue culture was studied. Luteinization of granulosa cells, as indicated by steadily increasing progesterone production (from 50 to 300 ng/10(5) cells/day over 4--5 days), was accompanied by a dramatic reduction in their capacity to aromatize exogenous androgen; oestradiol-17 beta production falling from 200 to less than 10 ng/10(5) cells/day over 4--5 days. Luteal cells also had only a very limited capacity to aromatize exogenous androgen, maximum oestradiol-17 beta production being less than 600 pg/10(5) cells/day. The loss in aromatizing capacity of granulosa cells during luteinization was also reflected in the relative endogenous steroid content of non-luteinized granulosa cells and luteal tissue, the former containing high levels of oestradiol-17 beta, less than or equal to 28 ng/mg protein, while the latter, although containing substantial amounts of testosterone, less than or equal to 5.7 ng/g tissue, contained very little oestradiol-17 beta, less than or equal to 0.35 ngG TISSUE. These findings suggest that luteinization of bovine granulosa cells and subsequent corpus luteum formation is associated with a loss in androgen aromatase activity.

Inhibin production by bovine ovarian tissues in vitro and its regulation by androgens

“…In vivo, intra-ovarian implants of the anti-androgen, flutamide, reduce the ability of porcine granulosa cells to secrete progesterone in vitro (Schomberg, Williams, Tyrey & Ulberg, 1978). While androgens failed to stimulate progesterone production by bovine follicular tissue and granulosa cells in this and other studies (Henderson & Moon, 1979;, a role for androgens in regulating bovine follicular progesterone production is suggested by the inhibitory action of cyproterone acetate. It is unlikely that the reduction in inhibin production by granulosa cells after cyproterone acetate treatment occurs as a consequence of the fall in progesterone production or vice versa.…”

“…A cytosolic receptor which after binding testosterone, is translocated to the nucleus is present in rat granulosa cells (Schreiber & Ross, 1976 (Table 2), thereby implicating androgen involvement in this process. Bovine granulosa cells isolated from antral follicles contain appreciable amounts of endogenous testosterone, in the order of 0-2-10 ng/mg protein (Henderson & Moon, 1979). The culture medium also contained small amounts of testosterone (<20 pg/ml) derived from the calf-serum.…”

Control of oestradiol secretion and of cytochrome P450 aromatase messenger ribonucleic acid accumulation by FSH involves different intracellular pathways in oestrogenic bovine granulosa cells in vitro

“…For example, culture of pig and bovine granulosa cells, especially in the presence of serum, leads to luteinization and loss of Cyp19 (Henderson & Moon 1979, Pescador et al 1999) that in rats is associated with marked changes in PKA signalling (Gonzalez-Robayna et al 1999). Changes in pathway use have recently been ascribed to changes in gonadotrophin receptor density in immature rat granulosa cells (Donadeu & Ascoli 2005).…”

Regulation of inhibin production by bovine ovarian cells in vitro

“…Granulosa cells harvested and pooled from antral follicles containing >0-3 ml follicular fluid were cultured as described previously (Henderson & Moon, 1979 (Eagle, 1959) and supplemented with Hepes buffer (20 mM), glutamine (2 mM), penicillin (50 units/ml), streptomycin (50 pg/ml), amphotericin (0-625 pg/ml) and non-essential amino acids (Eagle, 1959) (all reagents obtained from Flow Laboratories, Irvine, Scotland). The gas phase was air.…”