Human recombinant follistatin-288 suppresses plasma concentrations of follicle-stimulating hormone but is not a significant regulator of luteinizing hormone in castrated rams.
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.
Tilbrook
A J
AJ
Department of Physiology, Monash University, Clayton, Australia.
Clarke
I J
IJ
de Kretser
D M
DM
D000818:Animals; D005640:Follicle Stimulating Hormone / Q000097:blood*; D038681:Follistatin; D006023:Glycoproteins / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D009919:Orchiectomy; D011994:Recombinant Proteins / Q000494:pharmacology; D012756:Sheep
D038681:Follistatin; D006023:Glycoproteins; D011994:Recombinant Proteins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone