Recombinant growth hormone and insulin-like growth factor I do not alter gonadotrophin stimulation of the baboon testis in vivo.
In vitro studies indicate a physiological role for insulin-like growth factor I (IGF-I) in paracrine regulation of testicular function and recent clinical studies suggest a potential role for growth hormone (GH) and/or IGF-I in the treatment of hypogonadotrophic states in males. This study aimed to examine the effects of pretreatment with recombinant human GH (rhGH) or rhIGF-I on the response to gonadotrophins of the non-human primate testis in vivo. Using a balanced Latin square design with repeated measures, six prepubertal male hamadryas baboons (Papio hamadryas hamadryas) were treated in a cross-over sequence for periods of 18 days with daily im injections of rhGH (0.4 IU.kg-1.day-1), rhIGF-I (0.1 mg.kg-1.day-1) or saline with a 2-week washout period between each treatment. A single im injection of hCG (1500 IU) increased serum testosterone (p = 0.0002) but neither rhGH nor rhIGF-I influenced the timing or magnitude of this response (p > 0.5). A single im dose of FSH (75 IU) stimulated immunoreactive inhibin (p = 0.01) but also was unaffected in magnitude or timing by pretreatment with rhGH or rhIGF-I (p > 0.2). Circulating IGF-I levels were increased independently by hCG (p = 0.01) and FSH (p < 0.0001) administration. These findings indicate that neither GH nor IGF-I pre-treatment enhance acute gonadal responses to gonadotrophin stimulation of the prepubertal non-human primate testis in vivo. These findings suggest that GH or IGF-I treatment of hypogonadotrophic men without somatotrophin deficiency is unlikely to be beneficial.
Crawford
B A
BA
Department of Obstetrics and Gynaecology, University of Sydney, Australia.
Handelsman
D J
DJ
D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004347:Drug Interactions; D006062:Gonadotropins / Q000494:pharmacology*; D013006:Growth Hormone / Q000097:blood / Q000494:pharmacology* / Q000502:physiology; D007265:Inhibins / Q000097:blood / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000494:pharmacology* / Q000502:physiology; D008297:Male; D010215:Papio / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D013737:Testis / Q000187:drug effects / Q000502:physiology*; D013739:Testosterone / Q000097:blood / Q000378:metabolism
D006063:Chorionic Gonadotropin; D006062:Gonadotropins; D011994:Recombinant Proteins; D013739:Testosterone; D007265:Inhibins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone