Potentiation of the effect of an anesthetic, chloral hydrate, by stress and corticosterone: a behavioral study in the mouse

Many studies have demonstrated that stressors can modify the physiological action of drugs, mainly morphine. The present study investigated the effect s of a mild stressor on chloral hydrate (Chl)-induced sedation in mice. For 4 consecutive days, NaCl and Chi-treated mice (300 mg kg(-1)) were stresse d (S) either by a 5 min exposure to a brightly lit inescapable open field, or i.p. injected with corticosterone (Cor) (15 mg kg(-1)). Then, their spon taneous motor activity was recorded on an actisystem during 20 min and comp ared with that of the unstressed (US) NaCl and Chi-treated mice. On day 1 a nd 4, neither stressor nor i.p. administered Cor had any influence on the s pontaneous motor activity of NaCl-treated mice. In Chi-treated mice, the sp ontaneous motor activity was very low. On day 1, it was similar in S mice, Cor-injected mice, and US mice. On the contrary, on day 4, both stress and Cor enhanced the anesthetic-induced hypoactivity, showing that the magnitud e of sedation increased. It can then be stated that stressor, provided it w as repeatedly administered, potentiated the sedative action of chloral hydr ate and that such a potentiation was probably, but not only, Cor-dependent. Given that stress and Chi both produce dopamine overflow, it can be hypoth esized that S, potentiates the sedative action of Chi through a dopaminergi c link. (C) 2000 Elsevier Science B.V. All rights reserved.