Effect of Purified Relaxin on Uterine Glycogen and Protein in the Rat

Summary Purified, electrophoretically homogeneous porcine relaxin (1750 GPU/mg) increased uterine glycogen in both unprimed and estrogen-primed ovariectomized rats. In estrogen-primed animals the glycogenic response was linear with the logarithm of the dose from 3 to 30 μg/animal; in unprimed animals the effect of 10 μg was essentially the same as that achieved with 30 μg. Relaxin also increased wet and dry uterine weights and total nitrogen content, indicating true uterine growth. Uterotrophic, as well as glycogenic effects occurred without estrogen priming, although synergism of the two hormones was observed; this suggests that relaxin receptor concentrations in the uterus may be, to some degree, estrogen dependent. Relaxin did not affect the concentrations of diaphragm glycogen or plasma glucose; thus the direct effects of relaxin appear to be limited to control of metabolic events in the female reproductive system in a manner similar to insulin regulation of general body metabolism.