Relaxin causes changes of the liver. In vivo studies in rats

During pregnancy, the liver undergoes metabolic adjustments directed to ful fil the needs of the mother and the growing fetus. This study was designed to verify whether relaxin, a hormone related to pregnancy, may induce histo chemical and ultrastructural modifications of hepatocytes which can be rela ted to metabolic changes. Estrogen-primed female rats were treated with rel axin (10 mug in repository vehicle) for 18 h. Additional male rats were tre ated with relaxin (10 mug/day in PBS) for 4 days. Appropriate vehicle-treat ed rats were used as controls. After fasting, the rats were killed and live r fragments were processed for light and electron microscopy and for comput er-assisted morphometry of PAS-positive glycogen deposits and acid phosphat ase-reactive organelles. In both sexes, the relaxin-treated rats underwent a significant decrease in the amount of glycogen in the hepatocytes as comp ared with the controls. These changes were accompanied by an increase in sm ooth endoplasmic reticulum, endocytosis vesicles and lysosomes. These findi ngs show that relaxin promotes glycogen depletion and induces morphological changes of hepatocytes which are consistent with functional activation. It is suggested that relaxin might play an important role in hepatic metaboli c adjustments occurring during pregnancy.