Schwall, RalphSteiner, Robert A.Bremner, William J.Mason, Anthony J.Schmelzer, Charles H.McLachlan, Robert I.Dahl, Kristine D.2008-10-172008-10-171989-11Endocrinology. 1989 Nov;125(5):2787-9http://hdl.handle.net/1773/4343Activin-A is a homodimer of the beta A inhibin subunit that stimulates FSH secretion by pituitary cells in vitro; however, the physiological relevance of this effect is unknown. We have examined whether recombinant human activin-A (activin-A; 80 micrograms/kg/day iv infusion for 50.5 h) has in vivo bioactivity in the adult male macaque (n = 5). Serum FSH and LH bioactivity and serum testosterone (T) levels were measured on 2 control days and after 24 and 48 h of activin-A administration. Basal FSH levels increased significantly (p less than 0.05) by 17% at 24 h and 82% at 48 h during activin-A administration. No changes in basal LH or T levels were seen. The FSH and LH responses to GnRH (5 micrograms/kg, iv bolus) increased significantly (p less than 0.05) by 117% and 55% after 48 h of activin-A, respectively. A small (16%), but statistically significant (p less than 0.05), increase in the T response to the GnRH challenge was also noted. These data are preliminary evidence in support of a physiological role for activin-A in the control of gonadotropin secretion in the male primate.en-USandrologymale contraceptionklinefelter's syndrome5-alpha reductase inhibitorsspermatogenesiscolchicinereifenstein's syndromegonadotropinstestosteroneAnimalsReference ValuesResearch Support, Non-U.S. Gov'tActivinsFemaleGonadorelin, pharmacologyBiological AssayResearch Support, U.S. Gov't, P.H.S.Luteinizing Hormone, blood, pharmacology, secretionGranulosa Cells, drug effectsHumansMaleFollicle Stimulating Hormone, blood, pharmacology, secretionInhibins, pharmacologyResearch Support, U.S. Gov't, Non-P.H.S.Recombinant Proteins, pharmacologyMiceMacaca fascicularisArticle