High doses of systemic DHEA-sulfate do not affect sleep structure and elicit moderate changes in non-REM sleep EEG in rats

The hormone dchydroepiandrosterone (DHEA) and its metabolite DHEA-sulfate ( DHEAS) occur in huge quantities in the plasma as well as in the brain of ve rtebrates. To investigate whether DHEAS modulates sleep-wake behavior, we a ssessed the sleep response to three doses (25, 50, and 100 mg/kg) of intrap eritoneally administered DHEAS, mixed with oil, in 8 rats. DHEAS injections produced dose-dependent and long-lasting elevations in the plasma levels o f both DHEAS and DHEA. DHEAS administration did not affect sleep time and a rchitecture but exerted persistent effects on the electroencephalogram (EEG ) within non-rapid eye movement sleep: 50 mg/kg DHEAS significantly augment ed EEG power in the frequency range of sleep spindles, and 100 mg/kg DHEAS depressed EEG power in the slow-wave frequency bands. The findings indicate that DHEAS changes the sleep EEG in a dose-dependent way, possibly through a modulation of GABA- and glutamate-induced currents. (C) 2000 Elsevier Sc ience Inc. All rights reserved.