Journal article

HUMAN RECOMBINANT INHIBIN-A AND TESTOSTERONE ACT DIRECTLY AT THE PITUITARY TO SUPPRESS PLASMA-CONCENTRATIONS OF FSH IN CASTRATED RAMS

AJ TILBROOK, DM DEKRETSER, IJ CLARKE

JOURNAL OF ENDOCRINOLOGY | J ENDOCRINOLOGY LTD | Published : 1993

Abstract

The roles of inhibin and testosterone in the negative feedback control of the secretion of FSH were explored in experiments using castrated rams administered human recombinant inhibin A (hr-inhibin) and testosterone propionate (TP). Two experiments were conducted in the non-breeding season. In experiment 1, two groups of long-term castrated rams (wethers) were treated with an i.v. injection of either vehicle or hr-inhibin in two doses (25 and 50 micrograms) given 2 weeks apart. Plasma concentrations of FSH, measured by radioimmunoassay, were suppressed significantly (P < 0.01) and equally by both doses of hr-inhibin with a mean (+/- S.E.M.) maximal suppression of FSH of 19.9 +/- 2.60% occurr..

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