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Circadian variation in plasma dopamine levels in man
Journal of Endocrinological Investigation
|August 1, 1984
Summary
Plasma dopamine, norepinephrine, and epinephrine levels exhibit circadian patterns in recumbent males. Dopamine levels correlate more closely with clock time and show reduced secretion during sleep, suggesting shared regulatory mechanisms for catecholamines and sleep-wake cycles.
Area of Science:
- Neuroscience
- Endocrinology
- Chronobiology
Background:
- Catecholamines, including dopamine, norepinephrine, and epinephrine, are crucial neurotransmitters and hormones.
- Circadian rhythms significantly influence physiological processes, including hormone secretion.
- Understanding catecholamine patterns during rest and sleep is vital for comprehending neuroendocrine regulation.
Purpose of the Study:
- To investigate the diurnal and nocturnal secretory patterns of dopamine, norepinephrine, and epinephrine in normotensive males.
- To determine the relationship between plasma catecholamine levels and circadian rhythms.
- To explore potential common regulatory mechanisms for catecholamine secretion and sleep-wake cycles.
Main Methods:
- Collected plasma samples at 30-minute intervals over a 24-hour period from 9 normotensive males.
- Measured plasma concentrations of norepinephrine, epinephrine, and dopamine.
- Analyzed data for circadian patterns, correlations with clock time, and differences between sleep and awake states.
Main Results:
- Plasma levels of dopamine, norepinephrine, and epinephrine demonstrated significant circadian patterns in recumbent males.
- Dopamine levels showed a stronger correlation with clock time compared to norepinephrine and epinephrine.
- Dopamine secretion was notably reduced during the sleep period, with fewer secretory peaks and lower mean levels than during wakefulness.
- Strong positive correlations were observed between circadian changes in plasma dopamine and both norepinephrine (r=0.92) and epinephrine (r=0.78).
Conclusions:
- Plasma catecholamine levels, particularly dopamine, exhibit distinct circadian rhythms influenced by the sleep-wake cycle.
- The interrelationships between dopamine, norepinephrine, and epinephrine suggest a shared regulatory system governing both catecholamine secretion and rest-activity patterns.
- These findings contribute to understanding the neuroendocrine basis of circadian rhythms and their modulation by sleep.