PLASMA MELATONIN RHYTHM IS MAINTAINED IN HUMAN AFRICAN TRYPANOSOMIASIS

In human African trypanosomiasis (sleeping sickness), sleep and wake e pisodes are sporadically distributed throughout the day and the night. Plasma melatonin, sleep-wakefulness and rectal temperature rhythms we re studied in 9 Congolese patients suffering from sleeping sickness co mpared to 6 healthy controls submitted to the same light/dark regime. The circadian distribution of the sleep-wake cycle was disturbed in re lation to the severity of the disease, As controls, patients maintaine d a very distinct plasma melatonin nyctohemeral rhythm which displayed a significant phase advance(1:08 +/- 0:43 and 2:34 +/- 0:31 mean +/- SD, in patients and controls respectively; p < 0.01, U test), as well as a persistent rectal temperature rhythm (mesor 36,67 +/- 0.29 and 36 .74 +/- 0.13 degrees C, amplitude 0.29 +/- 0.16 and 0.32 +/- 0,13 degr ees C, acrophase 13:53 +/- 2:47 and 15:32 +/- 0:36 for patients and co ntrols respectively). No alteration of these rhythms was observed afte r treatment. In African controls we observed plasma melatonin characte ristics similar to those of European controls, especially for the onse t and the duration of the secretion and the stability of the rhythm, d espite a different light/dark regime. The dissociation observed betwee n the 3 rhythms (melatonin, temperature and sleep-wake cycle) is discu ssed, taking into consideration a functional compartmentalization of t he suprachiasmatic nuclei or more likely a disruption of the neural pa thway between the circadian clock and structures involved in the regul ation of the sleep-wake cycle, related to the activity of compounds re leased by the parasites or host cells.