title: The effect of atenolol, a beta1-adrenergic antagonist, on nocturnal plasma melatonin secretion: evidence for a dose-response relationship in humans.
abstract: Pineal beta1-adrenergic receptors are involved in the regulation of melatonin secretion. The involvement of beta1-adrenergic receptors has been demonstrated by the ability of acute administration of beta-antagonists to suppress the nocturnal rise of circulating melatonin and its urinary metabolite 6-sulphatoxymelatonin (aMT6s). The present study was undertaken to examine the relationship between increasing doses of atenolol and nocturnal plasma melatonin concentrations. Six healthy subjects participated in the study for a period of 5 weeks. Subjects were administered placebo, 12.5, 25, 37.5, and 50 mg doses of atenolol in a randomized single blind design. Each dose was separated by a 1 week washout period. Blood samples were collected at regular intervals from 19.00 hr to 06.00 hr. Repeated measures analysis of variance showed a dose-dependent decrease in plasma melatonin concentrations (P<0.01). A Student Newman-Keuls post hoc test indicated significant differences between placebo and all doses of atenolol (P<0.05). The results demonstrate a dose-dependent relationship between beta1-receptor blockade and suppression of nocturnal plasma melatonin in humans.
authors.affiliation: University of Melbourne, Department of Psychiatry, Austin and Repatriation Medical Centre, Heidelberg, Germany.
authors.forename: P J
authors.initials: PJ
authors.lastname: Nathan
authors.forename: K P
authors.initials: KP
authors.lastname: Maguire
authors.forename: G D
authors.initials: GD
authors.lastname: Burrows
authors.forename: T R
authors.initials: TR
authors.lastname: Norman
mesh_terms: D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage*; D000328:Adult; D001262:Atenolol / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008550:Melatonin / Q000097:blood*; D010870:Pineal Gland / Q000187:drug effects; D011863:Radioimmunoassay; D018342:Receptors, Adrenergic, beta-1 / Q000187:drug effects*; D016037:Single-Blind Method
chemical_list: D000319:Adrenergic beta-Antagonists; D018342:Receptors, Adrenergic, beta-1; D001262:Atenolol; D008550:Melatonin