SLEEP FRAGMENTATION, AND CHANGES IN LOCOMOTOR-ACTIVITY AND BODY-TEMPERATURE IN TRYPANOSOME-INFECTED RATS

The rest-activity and body temperature 24 h cycles, as well as the str ucture of spontaneous sleep, were studied in rats 3 weeks after infect ion with monomorphic Trypanosoma brucei brucei. This parasite belongs to the species of trypanosomes that causes in humans African sleeping sickness, a neuropsychiatric syndrome that involves alterations of end ogenous biological rhythms. In the infected rats, entrained to a 12 h: 12 h photoperiod, a considerable hypokinesia was detected during the h ours of darkness. A significant oscillation of the body temperature du ring 24 h was lost in some infected animals. In the other infected ani mals, the body temperature cycle displayed a lower amplitude and a pha se advance. The mean temperature was slightly higher in the infected t han in control rats during the period of light. A detailed analysis of the structure of spontaneous sleep, based on daytime electroencephalo graphic recordings, revealed during trypanosome infection an increased relative proportion of wake, and a decreased percent value of synchro nized sleep. A marked reduction of the mean REM latency and a fragment ed pattern of synchronized sleep, resulting in a considerable alterati on of the REM-non-REM sleep sequences, were also observed in the infec ted animals. These findings indicate that trypanosomiasis in the rat r esults in a striking sleep fragmentation, as well as in changes of loc omotor activity and body temperature rhythm. Thus, trypanosome infecti on in the rat provides an experimental model of sleep dysregulation in a structurally intact brain, and may provide an animal model of endog enous rhythm changes documented in African sleeping sickness.