Ultradian and circadian body temperature and activity rhythms in chronic MPTP treated monkeys

The body temperature and locomotor activity rhythms of seven 1-Methyl, 4-ph enyl, 1,2,3,6-tetrahydropyridine (MPTP)-treated cynomolgous monkeys were re gistered over a week on two separate occasions over an interval of 2 months . Motor disability was absent in two animals and present in five: it was mi ld in one, moderate in two and severe in two. Both temperature and motor ac tivity were recorded every minute using a radio telemetry system. Analysis of circadian rhythms revealed less robustness of the 24-hour circadian comp onents of body temperature and locomotor activity with increasing motor imp airment, and a fragmentation of the body temperature rhythm into 8 hour-per iod components. Both total activity and daytime activity correlated inverse ly with the degree of motor impairment, On the contrary, the monkeys did no t show differences in night time activity. The proportions of variance acco unted for by the body temperature and locomotor activity of 24 h + 12 h + 8 h components were correlated. Also, the average levels at which the circad ian rhythm varies between body temperature and locomotor activity were corr elated, The results were almost identical in the two 1-week recording sessi ons. The present study confirms individual differences in the vulnerability to M PTP of the nigrostriatal system of monkeys, suggesting that if a cumulative dose does not provoke stable motor alterations, this cumulative dose will not produce circadian body temperature and locomotor activity rhythm altera tions either. Similarly, if a dose is able to produce motor impairment, thi s dose will also be able to produce circadian rhythm alterations. (C) 2001 Editions scientifiques et medicales Elsevier SAS.