title: Opiate receptor activity of 17-alpha-estradiol and related steroids.
abstract: Of a large number of steroid hormones, semisynthetic analogues, and metabolites examined for activity in an opiate radioreceptor binding assay, only 17 alpha -estradiol (E-17 alpha) and closely related 17 alpha-dihydroequilin (DHE1) and 17 alpha-dihydroequilenin (DHE2) were active. 17 beta-estradiol (E-17 beta) was much weaker than E-17 alpha, particularly in the presence of Na+. On the basis of the effects of Na+ and Mn+2 on binding potency, E-17 alpha is an agonist/antagonist and DHE1 and DHE2 pure antagonists. There is evidence for diverse biological activities of 17-alpha estranes, some of which may be mediated through opiate receptors.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D045166:Estradiol Congeners / Q000494:pharmacology*; D007700:Kinetics; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects* / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D045166:Estradiol Congeners; D011957:Receptors, Opioid; D004958:Estradiol