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Preliminary Observations on the Suppression of Nocturnal Plasma Melatonin Levels by Short‐Term Administration of Diazepam in Humans
Author(s) -
Monteleone Palmiero,
Forziati Domenico,
Orazzo Catello,
Maj Mario
Publication year - 1989
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1989.tb00421.x
Subject(s) - melatonin , diazepam , endocrinology , medicine , placebo , gabaergic , circadian rhythm , analysis of variance , pharmacology , inhibitory postsynaptic potential , alternative medicine , pathology
Several studies suggest that GABAergic mechanisms may be involved in the modulation of melatonin secretion. However, conflicting results have been reported in animal studies; in humans the issue has not been widely investigated. In the present study, using a double‐blind design, six healthy men received orally, at midnight, 10 mg of diazepam, a GABAergic agent, or placebo, on two different occasions 1 week apart. Blood samples were collected, in the dark, immediately before the drug administration, and at 12:30, 1, 2, 3, and 4 AM. Serum melatonin was measured by a radioimmunological method with [ 125 I]melatonin as a tracer. Two‐way ANOVA with repeated measurements disclosed a significant effect for treatment ( P < 0.01), for time ( P < 0.0004), and for treatment X time interaction ( P < 0.05). Following diazepam administration, serum melatonin levels observed at 2, 3, and 4 AM were significantly lower than the corresponding values following placebo ( P < 0.02 at 2 and 4 AM; P < 0.03 at 3 AM [Students' paired t test]). These results show that nocturnal blood melatonin levels may be suppressed by the acute administration of a GABAergic agent, suggesting that GABA may be involved in the modulation of pineal activity in man.