Cellular localization of IGF-I and IGF-II mRNAs in immature hypophysectomized rat testis and epididymis after in vivo hormonal treatment.

IGF-I and II genes expression has been localized by in situ hybridization in testis and epididymis of immature hypophysectomized rats treated in vivo with either pFSH, hLH, bGH, hPRL or with saline. IGF-I mRNA expression was found in both Sertoli and Leydig cells after treatment with either FSH or LH. IGF-I mRNA was highly expressed in germ cells after FSH stimulation and to a lesser extent after GH or LH treatments. However, its expression was very low in hypophysectomized control or PRL treated rats. IGF-I mRNA was also expressed in stromal cells of epididymis after LH treatment and to a lesser extent after GH stimulation. In contrast, IGF-II mRNA expression was detected in all testicular cell types whatever the hormonal treatment (FSH, LH, GH, PRL). For each hormonal treatment testicular sections were examined after immunohistochemical staining with specific antisera against IGF-I and IGF-II. Both in situ hybridization and immunohistochemical data were examined in order to determine the testicular sites of synthesis of IGF-I and IGF-II.