Chronobiology of catecholamine excretion in different age groups

Area of Science:

• Chronobiology
• Endocrinology
• Pediatric and Geriatric Medicine

Background:

• Circadian rhythms regulate physiological processes, including hormone excretion.
• Age and sex can influence the excretion patterns of catecholamines (epinephrine, norepinephrine, dopamine).

Purpose of the Study:

• To investigate circadian and circannual rhythms of urinary catecholamine excretion in children and elderly individuals.
• To compare these rhythms between age groups and sexes.

Main Methods:

• Urine samples collected over 24-hour periods from children (11 +/- 1.5 years) and elderly subjects (77 +/- 8 years).
• Quantification of epinephrine, norepinephrine, and dopamine using High-Performance Liquid Chromatography (HPLC).
• Statistical analysis using cosinor and ANOVA to identify circadian and circannual variations.

Main Results:

• Both children and elderly subjects displayed circadian rhythms in urine volume and catecholamine excretion.
• Elderly subjects had higher urine volume, but children showed higher mesor (average level) for most catecholamines.
• Significant sex differences observed, with males generally exhibiting higher excretion than females.
• Circadian amplitudes varied, with higher values in children for some catecholamines.
• Elderly subjects showed a phase delay in circadian timing, with acrophase shifting to nighttime hours.
• Circannual variations in norepinephrine excretion were noted in winter for children and elderly women.
• Dopamine excretion showed a circannual rhythm in girls, peaking in fall.

Conclusions:

• Circadian and circannual rhythms of urinary catecholamine excretion differ between children and the elderly, as well as between sexes.
• Age-related changes in catecholamine excretion patterns are evident, particularly in circadian timing.
• Sex-specific differences in catecholamine excretion rhythms highlight the importance of considering sex in physiological studies.