GH-R have been demonstrated in fish hemopoietic cells. We ascertained that GH binding in our preparations was not due to blood cell contamination (data not shown); however, other testicular cells—such as endothelial cells, fibroblasts, or macrophages—are also susceptible to having GH-R, and more work will be necessary to investigate whether Sertoli cells are a mediator of GH action on spermatogenesis. buy ampicillin
In conclusion, a method for the measurement of GH-specific binding in crude testicular preparations has been validated in rainbow trout. This allowed us to demonstrate the presence of GH-R at all stages of spermatogenetic development. The marked decrease in testicular GH-R concentration during spermatogenesis is not related to the changes in hepatic GH-R concentration or to plasma GH concentrations. This decrease probably reflects the “dilution” of the cell type(s) carrying the receptors during the process of spermatogenetic development. Our data support the occurrence of GH-R in Sertoli cells without excluding their presence in other somatic cell types.