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Biology of Reproduction, Vol 53, 1353-1358, Copyright © 1995 by Society for the Study of Reproduction
ARTICLES |
AJ Tilbrook, IJ Clarke and DM de Kretser
Department of Physiology, Monash University, Clayton, Australia.
We have tested the hypothesis that treatment of castrated rams (wethers) with human recombinant follistatin-288 (FS-288) suppresses plasma concentrations of FSH but has no effect on plasma concentrations of LH. Wethers were given an i.v. injection of vehicle or 50 micrograms FS-288 followed by a 12-h i.v. infusion of vehicle or 800 micrograms FS- 288, respectively. This dose and treatment regimen was identical to that used in a previous study in which wethers were treated with vehicle or human recombinant inhibin A (hr-inhibin). Human recombinant follistatin significantly (p < 0.05) suppressed plasma concentrations of FSH, but vehicle had no effect. The maximal suppression of FSH occurred 12-15 h after the start of treatment, at which time the plasma concentrations were reduced by 20.6%. The reduction in plasma concentrations of FSH caused by FS-288 was about 2.6-fold less than that observed after the same treatment with hr-inhibin. FS-288 had no effect on plasma concentrations of LH; this result was similar to the findings we obtained with hr-inhibin. These data suggest that follistatin is a less potent negative regulator of FSH secretion than inhibin and that follistatin is not a significant regulator of the secretion of LH in rams.
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