Treatment of oophorectomized guinea pigs with intrauterine 17 beta-estradiol pellets may modulate myometrial beta-adrenergic receptor binding properties.
Intrauterine 17 beta-estradiol pellets can induce an up-regulation of guinea pig myometrial beta-adrenergic receptor density and l-isoproterenol-dependent adenylate cyclase activity. Does 17 beta-estradiol influence the ability of beta-adrenergic receptors to form a "high affinity" state with l-isoproterenol, which is a necessary step for adenylate cyclase activation? Nonpregnant, oophorectomized guinea pigs received intrauterine pellets of either placebo, 17 beta-estradiol, progesterone, or 17 beta-estradiol plus progesterone for 1 week. 17 beta-Estradiol resulted in pharmacologic, whereas progesterone resulted in physiologic plasma 17 beta-estradiol and progesterone concentrations, respectively. The affinity of myometrial beta-adrenergic receptors for l-isoproterenol was measured by percentage of inhibition of -[125I]cyanopindolol binding. In all groups, the competition curves in the presence of magnesium chloride could be resolved into two affinity states of the beta-adrenergic receptor, "high" and "low," respectively. The ratio of their dissociation constants was not influenced by hormonal treatment. However, the relative concentration of beta-adrenergic receptors in the high affinity state was significantly higher in the 17 beta-estradiol-treated group than that in the control group. This correlates with the up-regulation in myometrial adenylate cyclase activity and suggests that myometrial beta-adrenergic receptor-adenylate cyclase function may be modulated by 17 beta-estradiol.
Hatjis
C G
CG
Department of Obstetrics and Gynecology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina.
Grogan
D M
DM
Koritnik
D R
DR
D000319:Adrenergic beta-Antagonists / Q000378:metabolism; D000818:Animals; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006160:Guanosine Triphosphate / Q000378:metabolism; D006168:Guinea Pigs; D007545:Isoproterenol / Q000378:metabolism; D009215:Myometrium / Q000378:metabolism*; D010052:Ovariectomy; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism
D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta; D011374:Progesterone; C047975:cyanopindolol; D004958:Estradiol; D006160:Guanosine Triphosphate; D010869:Pindolol; D007545:Isoproterenol