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 infection with Trypanosoma brucei brucei. In the infected rats, which were entrained to a 12 hours/12 hours photoperiod, a considerable hypokinesia was detected during the hours of darkness. In most of the infected animals, the body temperature cycle displayed a lower amplitude and an advance of about 3 hours in respect to control rats; in addition, the body temperature rhythm was not significant in some infected rats. The relative proportion of slow wave synchronized sleep, as well as the rapid-eye movement (REM) latency, were significantly reduced in the infected animals, in which sleep was considerably fragmented. The induction of Fos (the protein encoded by the immediate early gene c-fos), in response to light stimulation during the early subjective night, was severely impaired in the hypothalamic suprachiasmatic nuclei in trypanosome-infected rats. Altogether these data point out a disruption of locomotor activity and body temperature 24 hours cycle and a major disorganization of sleep during experimental trypanosomiasis. In addition, our findings indicate that the molecular and functional correlates of the synchronizing action of the suprachiasmatic nuclei, which play a major role of biological clock of endogenous biological rhythms, could be altered during trypanosome infection.