NORADRENALINE NEUROTOXIN DSP-4 EFFECTS ON SLEEP AND BRAIN TEMPERATUREIN THE RAT

N(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) has a selective de generative effect on noradrenergic fibers originating from locus coeru leus (LC) neurons. In the present study, we studied its effect on vigi lance states and brain temperature by continuous recordings for period s of 1-5 days and 2-4 weeks following DSP-4 treatment. On the first da y, paradoxical sleep duration was significantly decreased (-67%, P < 0 .05), slow-wave sleep (SWS) duration increased (+16%, P < 0.05) up to 48 h after DSP-4 treatment (+8%, P < 0.05) and the wake period decreas ed (-8%, P < 0.05). The vigilance states returned to control values 4- 5 days later. The brain temperature was decreased during the first nig ht (-2 degrees C) and then recovered the control values. Two and 4 wee ks after DSP-4 treatment, paradoxical sleep was still decreased (-18% and -23%, respectively, P < 0.05), while SWS was significantly increas ed only at night during the fourth week (+23%, P < 0.05). These result s therefore provide evidence for a differential involvement of the nor adrenergic LC system in sleep mechanisms depending on the light-dark c ycle. Different hypotheses are proposed. (C) 1998 Elsevier Science Ire land Ltd. All rights reserved.