[IGF(s) and testicular functions. Secretion and action of IGF-1 on Leydig cells].
Many in vitro and in vivo studies have demonstrated a presence of IGF-I in the testis. Testicular production of IGF-I and its mRNA is stimulated largely by gonadotropins; FSH acts on Sertoli cells while LH acts on Leydig cells. A regulation by local factors is also demonstrated; the role of GH remains unclear. In the testis, IGF-I has various effects but we only focussed this review on Leydig cells. Specific receptors have been characterized on these cells. They are up-regulated by LH/hCG (at the transcriptional level) and down regulated by IGF-I. The effect of GH is depend on the experimental models used. In addition in this paper, we have shown in adult rats that the IGF-I level in the testicular interstitial fluid and the IGF-I receptors on Leydig cells are modified by fasting. Both in vivo and in vitro, IGF-I increased LH/hCG receptors and the steroïdogenic response to hCG by a mechanism which is poorly understood yet.
Grizard
G
G
Laboratoire de Biologie de la Reproduction, Faculté de Médecine, Clermont-Ferrand.
D000818:Animals; D006063:Chorionic Gonadotropin / Q000502:physiology; D005640:Follicle Stimulating Hormone / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D007985:Leydig Cells / Q000502:physiology*; D007986:Luteinizing Hormone / Q000502:physiology; D008297:Male; D051381:Rats; D013737:Testis / Q000502:physiology*
D006063:Chorionic Gonadotropin; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone
IGF(s) et fonctions testiculaires. Sécrétion et action de l'IGF-I sur la cellule de Leydig.