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 from that observed in mammals: large increases in hepatic GH binding and/or of GH-R mRNA were seen during sexual maturation in rodents. asthma inhalers
This evolution may be related to the rapid growth and to the metabolic status of these animals during puberty rather than to their reproductive/sexual status. The significantly lower GH-R levels observed in trout in stage VI could be accounted for by nutritional or temperature effects, since at approximately that period the fish were given a reduced food ration to compensate for the large increase in water temperature that occurred at the end of summer during our experimentation. Indeed, decreased liver GH-R have been shown to occur in the case of food restriction or increased rearing temperature in teleost fish as in higher vertebrates.