Posts Tagged ‘Growth Hormone

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 […]

The presence of GH-R in Sertoli cells is also strongly suggested in the present work. In preliminary studies with different populations of isolated testicular cells, high-affin-ity GH binding sites could be detected in cultures enriched in Sertoli cells but not in round germ cells, in spermatozoa, or in mixed testicular cell populations. Furthermore, the marked […]

We hypothesize that the decrease in testicular GH-R concentration reflects the fact that GH-R are localized in one or several cell populations the proportion of which decreases rapidly when spermatogenesis develops. Only two studies have presented information on GH-R distribution in testis: in the rat, Lobie et al. reported a strong GH-R/GH-BP immunoreactivity in Leydig […]

Changes in hepatic and testicular GH-R concentration were quite different, suggesting that the evolution observed in these two organs did not have the same causes. This is in agreement with recent studies in higher vertebrates demonstrating that the regulation of GH-R expression is tissue specific. Hepatic GH-R have been found to be either up- or […]

We further analyzed these changes by comparing the evolution of testicular GH-R concentration, hepatic GH-R concentration, and plasma GH levels. In comparison with observations for testicular GH-R, more modest changes occurred in liver GH-R concentrations during the reproductive cycle. Hepatic GH-R were slightly decreased during most of the spermatogenetic cycle (stages III-VII). This evolution differs […]

To our knowledge this is the first report on the changes in GH-R in testicular tissue during a spermatogenetic cycle in a vertebrate. Relatively large numbers of GH-R were present in the immature trout testis, that is, before any sign of spermatogenetic development could be detected. At that stage, somatic cells and stem germ cells […]

Our results reveal that the characteristics (affinity, specificity) of GH binding to crude testicular homogenates are identical to those described in rainbow trout crude hepatic preparations (this study; ) and in hepatic or testicular membrane preparations (this study; ). Binding was specific to GH with little or no affinity for other hormones. Other studies also […]