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Alpha-methyl-p-tyrosine shifts circadian temperature rhythms
The American Journal of Physiology
|September 1, 1982
Summary
Alpha-Methyl-p-tyrosine alters rat body temperature rhythms, with effects depending on administration timing. Norepinephrine turnover in the hypothalamus correlates with these phase shifts, suggesting its role in regulating circadian rhythms.
Area of Science:
- Chronobiology
- Neuropharmacology
- Physiology
Background:
- Circadian rhythms govern physiological processes, including body temperature cycles.
- The neurotransmitter norepinephrine is implicated in regulating biological rhythms.
- Understanding how external factors influence circadian rhythms is crucial for chronopharmacology.
Purpose of the Study:
- To investigate the effects of alpha-Methyl-p-tyrosine on the circadian temperature rhythm in rats.
- To determine if the timing of drug administration influences the observed phase shifts.
- To explore the relationship between norepinephrine turnover and drug-induced circadian rhythm alterations.
Main Methods:
- Rats were administered alpha-Methyl-p-tyrosine methyl ester HCl (100 mg/kg) at different phases of their light-dark cycle.
- Intraperitoneal temperature rhythms were monitored to assess acrophase shifts (timing of highest temperature).
- Norepinephrine turnover in the hypothalamus was measured and correlated with temperature rhythm phase shifts.
Main Results:
- Administration during the late light phase delayed the temperature rhythm acrophase by up to 3 hours.
- Administration during the dark phase advanced the acrophase by approximately 2 hours.
- Phase shifts were correlated with the timing of norepinephrine turnover in the hypothalamus.
Conclusions:
- Alpha-Methyl-p-tyrosine can phase-shift the rat circadian temperature rhythm.
- Norepinephrine turnover in the hypothalamus appears to play a role in regulating these circadian temperature rhythms.
- The timing of drug administration significantly impacts its effects on circadian rhythms, highlighting the importance of chronopharmacological considerations.
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