Estrogen-related increases in uterine guanosine 3':5'-cyclic momophosphate levels.

Endogenous uterine cyclic GMP and cyclic AMP concentrations were monitored at each stage of the estrus cycle; cyclic GMP concentrations were found to be highest and cyclic AMP concentrations lowest during proestrus when plasma estrogen levels have been shown to be maximal. After administration of estradiol-17beta or diethylstilbestrol, the concentrations of uterine cyclic GMP in ovariectomized rats underwent a progressive and significant elevation and the levels of cyclic AMP declined significantly below control values when near maximal accumulation of tissue cyclic GMP was achieved. The increase in uterine cyclic GMP concentrations produced by estradiol benzoate administration was prevented when progesterone and the estrogen were co-administered. These results raise the possibility that an enhanced cellular accumulation of cyclic GMP may be involved in the expression of some of the actions of estrogen in uterine tissue.