Age-Related Decreases in Melatonin Secretion—Clinical Consequences

作者：Richard Jay Wurtman · 发表于：The Journal of Clinical Endocrinology & Metabolism · 年份：2000 · DOI：10.1210/jcem.85.6.6660 · 被引用次数：36 · 研究领域：Circadian rhythm and melatonin、Sleep and Wakefulness Research、Infant Health and Development

Pineal glands of humans and other mammals secrete melatonin at nighttime, thereby generating the now familiar circadian rhythms in plasma and urinary melatonin levels (1). But, although the hormone’s plasma levels at nighttime remain at least an order of magnitude higher than at daytime throughout the life span, its absolute concentrations undergo a continuing decline after peaking at ages 2–5 yr (2–4). This decline could be related to the failure of the pineal—unlike the pituitary—to grow, to its still unexplained tendency to calcify, or even to effects of other age-dependent hormones on pineal cells or their neural inputs. The reductions in nocturnal plasma melatonin that occur around pubescence could be a factor in causing the sexual maturation, if melatonin is an endogenous gonad-inhibitor in people as it is in some laboratory rodents. However, the evidence for such an antigonadal effect is minimal. In contrast, compelling evidence is available that the reductions that occur later in life do have a clinically relevant consequence (i.e. the insomnia observed in at least some of the older people who suffer from this condition): normal sleep can often be restored by administering doses of the hormone that raise nighttime plasma melatonin levels to what they were earlier in adult life (i.e. 100–200 pcg/mL) (4, 5, 5A ). It had previously been proposed that the decline in melatonin secretion observed toward the end of the first decade of life depends not on the individual’s age...