title: Aging and the circadian rhythm of melatonin: a cross-sectional study of Chinese subjects 30-110 yr of age.
abstract: Although previous reports indicate that nocturnal plasma melatonin secretion declines with age, some recent findings do not support this point. In the present cross-sectional study, we documented serum melatonin concentrations at two time points, 02:00 and 08:00 h, in 144 persons aged 30-110 yr and found a significant age-related decline. It began around the age of 60 and reached a very significantly lower level in subjects in their 70s and over 80 yr of age (P < 0.01, when compared with age <60 yr). Nocturnal melatonin levels were higher among (post-menopausal only) women than men overall (P < 0.05). In the older age-groups, nocturnal melatonin levels did not differ between healthy controls and subjects with high blood pressure or ischemic heart disease. To further check these results, we also assessed the circadian pattern of serum melatonin in four subgroups of healthy men, aged 30-39, 40-49, 50-59, and 60-69 yr: blood samples were taken at 2 h intervals from 08:00 to 22:00 h and hourly from 22:00 to 08:00 h. Our results showed generally similar circadian melatonin patterns that peaked at night with very low levels during the daytime. No significant difference was found among the three younger groups, but nocturnal melatonin levels were significantly lower in the men in their 60s.
authors.affiliation: Anti-Senility Research Center of Shandong, Shandong Academy of Medical Sciences, 250062 Jinan, PR China.
authors.forename: Zi-Yan
authors.initials: ZY
authors.lastname: Zhao
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
authors.forename: Yue-Rong
authors.initials: YR
authors.lastname: Fu
authors.forename: André
authors.initials: A
authors.lastname: Bogdan
authors.forename: Yvan
authors.initials: Y
authors.lastname: Touitou
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D002681:China; D002940:Circadian Rhythm / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008550:Melatonin / Q000097:blood*; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D017440:Photoperiod; D013997:Time Factors
chemical_list: D008550:Melatonin