Estrogen increases adrenergic- but not cholinergic-mediated production of inositol phosphates in rabbit uterus

RK Riemer, A Goldfien and JM Roberts

Department of Obstetrics-Gynecology and Reproductive Sciences, University of California, San Francisco 94143.

alpha 1-Adrenergic and muscarinic cholinergic stimuli activate uterine contraction. Estrogen increases adrenergic but not cholinergic sensitivity of rabbit myometrium independent of its effects on adrenoceptor concentration. Since both alpha 1-adrenergic and muscarinic receptors are coupled to phosphatidylinositol hydrolysis, we tested the hypothesis that estrogen increases adrenergic- but not cholinergic-mediated inositol triphosphate production. We found that maximal production of inositol phosphates stimulated by norepinephrine was increased approximately 3-fold following estrogen treatment. Cholinergic-stimulated production was not increased by estrogen treatment. These results demonstrate that the effect of estrogen to enhance uterine adrenergic sensitivity is associated with an increased post-receptor response. The nature of the selectivity of estrogen for adrenergic versus cholinergic response remains obscure, but the results suggest the presence of parallel pathways for receptor activation of a common post-receptor response.

Volume 32, Issue 5, pp. 663-668, 11/01/1987
Copyright © 1987 by American Society for Pharmacology and Experimental Therapeutics

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