title: Diurnal differences in L-tryptophan sleep and temperature effects in the rat.
abstract: Sleep/waking and EEG power spectra were investigated for 6 h periods in rats following administration of the essential amino acid L-tryptophan (40 mg/kg), the selective serotonin uptake inhibitor zimeldine (20 mg/kg), and following a combination of L-tryptophan and zimeldine. In contrast to earlier studies, L-tryptophan decreased waking and increased total slow wave sleep when administered late in the light phase (8 1/2 h after light onset). No sleep effects were seen after early light phase injections (2 h after lights on). In agreement with earlier studies, zimeldine initially increased wakefulness, followed by an increase in slow wave sleep-2. REM sleep was abolished after zimeldine treatment. Zimeldine increased EEG delta activity and decreased EEG activity above 7 Hz. L-Tryptophan potentiated the zimeldine induced increase in waking only when given early in the light phase. In a separate experiment, body temperature was monitored after L-tryptophan injections in both early and late light phase. A thermogenic effect of L-tryptophan was seen in the early light phase, while the opposite was seen in the late light phase. The data indicate diurnal differences in sleep/waking and temperature effects of a physiological dose of L-tryptophan.
authors.affiliation: Department of Physiology, University of Bergen, Norway.
authors.forename: O E
authors.initials: OE
authors.lastname: Olsen
authors.forename: D
authors.initials: D
authors.lastname: Neckelmann
authors.forename: R
authors.initials: R
authors.lastname: Ursin
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D002940:Circadian Rhythm / Q000502:physiology*; D004347:Drug Interactions; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000187:drug effects; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012890:Sleep / Q000187:drug effects*; D012895:Sleep, REM / Q000187:drug effects; D014364:Tryptophan / Q000494:pharmacology*; D014851:Wakefulness / Q000187:drug effects; D015031:Zimeldine / Q000494:pharmacology
chemical_list: D015031:Zimeldine; D014364:Tryptophan