LHRH - modulator of progesterone and estradiol secretion by theca and granulosa cells on porcine follicle in mono- and co-culture.

Progesterone (P4) and estradiol (E2) secretion by granulosa and theca cells cultured alone or in co-culture under the influence of LHRH was studied. Follicular cells were separated from the follicles of different size: small (1-3 mm), middle (4-6 mm) and large (7-10 mm). The cells were cultured in medium M199 containing 100 ng LH/ml for 30 h. LHRH in a dose of 10[-8] M was added to LH treated cultures after 24 h in culture. Then the cultures were incubated with this hormone during subsequent 6 h. LHRH significantly increased LH-stimulated E2 secretion by granulosa cells (GC) harvested from small and middle follicles, but not from large ones. LHRH had no effect on P4 secretion by granulosa cells alone from small and middle follicles, but it significantly decreased P4 secretion in cultures of granulosa cells harvested from large follicles. In cultures of theca layers (T) alone, decreased secretion of E2 was observed from small follicles only. LHRH had no effect on P4 secretion by theca cell from large follicles cultured alone. However, it markedly increased P4 secretion by T cells from middle follicles and decreased that by theca cells from small follicles. In co-culture of granulosa and theca cells resembling an in vivo follicle, the addition of LHRH to LH stimulated cells harvested from small and middle follicles caused an increase of E2 and decrease of P4 secretion. On the other hand, in co-cultures of cells from large preovulatory follicles, both E2 and P4 secretion was suppressed. It may be concluded that the diverse effects of LHRH (either inhibitory or stimulatory) depend on the degree of follicular maturation.