In vitro evidence of a role for inhibin in female rabbits.
To examine a regulatory role for inhibin in female rabbits, an in vitro bioassay for inhibin activity was modified to use cultured rabbit pituitary cells and charcoal-extracted porcine follicular fluid (pFFx) as a reference preparation. pFFx inhibited follicle-stimulating hormone (FSH) release in a dose-dependent manner in cultures from both intact (I) and castrate (C) does at doses that also inhibited FSH release by cultured rat pituitary cells. Basal FSH release by I cells was inhibited greater than 10% by 0.02% (vol/vol) and greater than 90% by greater than or equal to 0.2% pFFx, whereas in C cells maximal inhibition of FSH release plateaued at only approximately 75%. FSH secretion was restored after removal of pFFx in day 2 media. Luteinizing hormone (LH) release by C cells was not inhibited at any dose of pFFx, but in I cells LH was progressively inhibited to approximately 60% of control levels during day 2 (but not day 1). Charcoal-extracted media (0.25-1%) in which 5 X 10(5) rabbit granulosa cells had been earlier cultured for 72 h produced a parallel inhibition of FSH release. The present findings demonstrate that 1) rabbit pituitary cells are responsive to inhibin, i.e., pFFx preferentially inhibited FSH secretion in a direct, graded, and reversible manner and 2) rabbit follicular granulosa cells secrete an inhibin-like substance.
D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D005640:Follicle Stimulating Hormone / Q000037:antagonists & inhibitors / Q000378:metabolism; D006107:Granulosa Cells / Q000378:metabolism; D066298:In Vitro Techniques; D007265:Inhibins / Q000494:pharmacology / Q000502:physiology*; D007986:Luteinizing Hormone / Q000378:metabolism; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism; D011817:Rabbits / Q000502:physiology*
D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone