Estrogen increases adrenergic- but not cholinergic-mediated production of inositol phosphates in rabbit uterus.
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.
Riemer
R K
RK
Department of Obstetrics-Gynecology and Reproductive Sciences, University of California, San Francisco 94143.
Goldfien
A
A
Roberts
J M
JM
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007295:Inositol Phosphates / Q000096:biosynthesis*; D007700:Kinetics; D009638:Norepinephrine / Q000494:pharmacology; D010052:Ovariectomy; D011224:Prazosin / Q000494:pharmacology; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D013403:Sugar Phosphates / Q000096:biosynthesis*; D014590:Uterine Contraction / Q000187:drug effects; D014599:Uterus / Q000187:drug effects / Q000378:metabolism*; D015016:Yohimbine / Q000494:pharmacology
D007295:Inositol Phosphates; D011942:Receptors, Adrenergic, alpha; D011976:Receptors, Muscarinic; D013403:Sugar Phosphates; D015016:Yohimbine; D004958:Estradiol; D002217:Carbachol; D009638:Norepinephrine; D011224:Prazosin