Inverse effects of activin and inhibin on the synthesis and secretion of FSH and LH by ovine pituitary cells in vitro.
Little information is available on the effects of activin and inhibin on the synthesis and secretion of pituitary gonadotrophins in species other than the rat. In this in-vitro study, ovine pituitary cell cultures derived from immature sheep were used to investigate the effects of recombinant human activin-A and native Mr 32,000 bovine inhibin on basal and gonadotrophin-releasing hormone (GnRH)-induced release of FSH and LH. Residual cellular contents of FSH and LH were also determined, allowing total content/well to be calculated. Activin-A promoted a dose-dependent increase in basal (+72%; P less than 0.001) and GnRH-induced (+25%; P less than 0.001) release of FSH as well as in the residual cell content (+114%; P less than 0.001) and total FSH content/well (+67%; P less than 0.001). Conversely, inhibin significantly (P less than 0.001) suppressed each aspect of FSH production examined, confirming that in sheep, as in rats, activin and inhibin exert opposing effects on pituitary FSH production. In contrast to the rat, however, in which activin is reported to have no effect on LH secretion, exposure of sheep pituitary cells to activin-A promoted a dose-dependent suppression (-42%; P less than 0.001) of GnRH-induced LH release. This was associated with a corresponding increase (P less than 0.001) in residual cellular content of LH. Consistent with a previous report from this laboratory, inhibin had the opposite effect and significantly enhanced (+47%; P less than 0.001) GnRH-induced LH release. This was associated with a corresponding fall (P less than 0.01) in residual cellular content of LH.(ABSTRACT TRUNCATED AT 250 WORDS)
Muttukrishna
S
S
Department of Biochemistry & Physiology, The University, Whiteknights, Reading.
Knight
P G
PG
D028341:Activins; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005640:Follicle Stimulating Hormone / Q000096:biosynthesis* / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007265:Inhibins / Q000494:pharmacology*; D007700:Kinetics; D007986:Luteinizing Hormone / Q000096:biosynthesis* / Q000378:metabolism; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism*; D012756:Sheep
D028341:Activins; D007987:Gonadotropin-Releasing Hormone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone