In teleost fish, binding sites for homologous GH have been detected in the testis , and Le Gac et al. have, for the first time in a vertebrate, described GH-specific binding with general characteristics of GH-R in rainbow trout testicular membrane preparations. Other studies suggest that these GH-R are functional. Indeed, GH treatments are able to modify, in vivo and in vitro, the production of sexual steroids at the gonad level in teleost fish and to modify testicular IGF-I mRNA content in rainbow trout. ventolin inhaler
The physiological role of GH in gonadal development during puberty and spermatogenesis is not known. In order to progress in this field, changes in GH-R concentration in the testis as well as the target cells for this hormone at various stages of testicular development should be determined. The objective of this study was to investigate the changes in testicular GH-R during the spermatogenetic cycle of rainbow trout. To achieve this, we first needed to characterize the specific binding of GH to crude testicular preparation and to validate this method to allow studies in individual testes or in pools of small-sized gonads. We also attempted to analyze the evolution of testicular GH-R during spermatogenesis by examining and comparing, across the same period, the pattern of hepatic GH-R and plasma GH concentration. Finally, we initiated the study of GH-R cellular distribution in the testis by using isolated testicular cell populations.