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Ultradian and circadian body temperature and activity rhythms in chronic MPTP treated monkeys
H Almirall1, V Bautista, A Sánchez-Bahillo
1Departamiento de Psiquiatria i Psicobiologia Clinica, Universitat de Barcelona, Barcelona, Spain. ealmirall@psi.ub.es
Abstract:
The body temperature and locomotor activity rhythms of seven 1-Methyl, 4-phenyl, 1,2,3,6-tetrahydropyridine (MPTP)-treated cynomolgous monkeys were registered 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 mild in one, moderate in two and severe in two. Both temperature and motor activity were recorded every minute using a radio telemetry system. Analysis of circadian rhythms revealed less robustness of the 24-hour circadian components of body temperature and locomotor activity with increasing motor impairment, and a fragmentation of the body temperature rhythm into 8 hour-period components. Both total activity and daytime activity correlated inversely with the degree of motor impairment. On the contrary, the monkeys did not show differences in night time activity. The proportions of variance accounted 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 circadian rhythm varies between body temperature and locomotor activity were correlated. The results were almost identical in the two 1-week recording sessions. The present study confirms individual differences in the vulnerability to MPTP 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 alterations either. Similarly, if a dose is able to produce motor impairment, this dose will also be able to produce circadian rhythm alterations.
Insights
Motor impairment in MPTP-treated monkeys disrupts body temperature and activity rhythms. Less motor impairment means more robust circadian rhythms, while severe impairment fragments the body temperature rhythm.
Area of Science:
- Neuroscience
- Chronobiology
- Primate Models
Background:
- 1-Methyl, 4-phenyl, 1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin used to model Parkinson's disease.
- Circadian rhythms, including body temperature and locomotor activity, are crucial for physiological regulation.
- MPTP-induced neurotoxicity can affect motor function and potentially disrupt biological rhythms.
Purpose of the Study:
- To investigate the impact of MPTP-induced motor impairment on circadian rhythms in cynomolgous monkeys.
- To determine the relationship between the degree of motor disability and alterations in body temperature and locomotor activity rhythms.
- To assess the predictive value of motor impairment for circadian rhythm disturbances.
Main Methods:
- Seven cynomolgous monkeys were treated with MPTP.
- Body temperature and locomotor activity were continuously monitored using radio telemetry over one week, repeated after two months.
- Motor disability was assessed and categorized (absent, mild, moderate, severe).
Main Results:
- Increasing motor impairment correlated with reduced robustness of 24-hour circadian components for both body temperature and activity.
- Severe motor impairment led to fragmentation of the body temperature rhythm into 8-hour components.
- Total and daytime activity levels were inversely correlated with motor impairment severity, while nighttime activity remained unaffected.
Conclusions:
- MPTP-induced motor impairment significantly disrupts circadian rhythms in monkeys.
- The degree of motor disability is a reliable indicator of circadian rhythm alterations.
- Individual differences in nigrostriatal system vulnerability influence both motor and circadian responses to MPTP.