Adrenergic regulation of estradiol uptake and cyclic GMP content in rat uterus

The presence of adrenergic regulation of estradiol uptake in rat uterus was studied by using alpha- and beta-adrenergic blockers in normal or Ca2+-free Tyrode's solution at 30 degrees C in vitro. Cyclic GMP content was also investigated under these conditions. By the stimulation with noradrenaline (4 X 10(-7) M), Ca2+-dependent 3H-estradiol uptake was increased in both cytosol and nuclear fractions. These increases were blocked in the presence of phentolamine (4 X 10(-7) M) but not by propranolol (4 X 10(-7) M). Increase in uterine cyclic GMP contents were shown under the condition in which 3H-estradiol uptake was stimulated. These results suggest that adrenergic alpha-stimulation increased uterine estradiol uptake and that consequently, increased estradiol-receptor complexes elevated uterine cyclic GMP levels. The changes in uterine cyclic GMP may serve as an index of estrogen action.