SLEEP AND TIMEKEEPING CHANGES, AND DYSREGULATION OF THE BIOLOGICAL CLOCK IN EXPERIMENTAL TRYPANOSOMIASIS

The rest-activity and body temperature 24 hours cycles, as well as the pattern of spontaneous sleep, were investigated in rats after infecti on with Trypanosoma brucei brucei. In the infected rats,,which were en trained to a 12 hours/12 hours photoperiod, a considerable hypokinesia was detected during the hours of darkness. In most of the infected an imals, the body temperature cycle displayed a lower amplitude and an a dvance of about 3 hours in respect to control rats; in addition, the b ody temperature rhythm was not significant in some infected rats. The relative proportion of slow wave synchronized sleep, as well as the ra pid-eye movement (REM) latency, were significantly reduced in the infe cted animals, in which sleep was considerably fragmented The induction of Fos (the protein encoded by the immediate early gene c-fos), in re sponse to light stimulation during the early subjective night, was sev erely impaired in the hypothalamic suprachiasmatic nuclei in trypanoso me-infected rats. Altogether these data point out a disruption of loco motor activity and body temperature 24 hours cycle and a major disorga nization of sleep during experimental trypanosomiasis. In addition, ou r findings indicate that the molecular and functional correlates of th e synchronizing action of the suprachiasmatic nuclei, which play a maj or role of biological clock of endogenous biological rhythms, could be altered during trypanosome infection.