Ferrari E, Magri F, Dori D, Migliorati G, Nescis T, Molla G, Fioravanti M, Solerte S B
Department of Internal Medicine and Medical Therapy, University of Pavia, Italy.
Neuroendocrinology. 1995 Apr;61(4):464-70. doi: 10.1159/000126869.
Physiological brain aging is characterized by important biochemical and structural changes and by the unbalance among the different neurotransmitters and neuromodulators. The study of the circadian organization of neuroendocrine functions may be considered a clinically reliable tool to investigate the changes of the CNS and particularly of the limbic-hypothalamic system occurring in aged people. The circadian rhythms of plasma melatonin, ACTH and cortisol and of oral temperature were studied in 16 clinically healthy women aged 66-90 years and in 14 young controls aged 20-30. In addition, the effect of dexamethasone on the plasma cortisol circadian rhythm and the cortisol response to Synacthen pulse intravenous injection were evaluated. All subjects were studied as inpatients, with the same synchronization to the hospital life schedule. When compared with young controls, elderly subjects exhibited a reduction of the mean level and of the amplitude of the circadian rhythm of oral temperature, an increase of the mean level of ACTH and cortisol rhythms and a selective impairment of melatonin nocturnal secretion. Furthermore, elderly subjects showed a reduced sensitivity to the dexamethasone suppression test, by comparison to young controls. These changes were age-related and they may depend either on CNS modification or on alterations of the hormonal metabolic clearance.
生理性脑老化的特征是重要的生化和结构变化，以及不同神经递质和神经调质之间的失衡。神经内分泌功能昼夜节律组织的研究可被视为一种临床可靠的工具，用于研究老年人中枢神经系统尤其是边缘-下丘脑系统发生的变化。对16名年龄在66至90岁的临床健康女性和14名年龄在20至30岁的年轻对照者的血浆褪黑素、促肾上腺皮质激素（ACTH）、皮质醇昼夜节律以及口腔温度进行了研究。此外，评估了地塞米松对血浆皮质醇昼夜节律的影响以及皮质醇对合成促肾上腺皮质激素（Synacthen）脉冲静脉注射的反应。所有受试者均作为住院患者进行研究，与医院生活时间表同步。与年轻对照者相比，老年受试者口腔温度昼夜节律的平均水平和振幅降低，ACTH和皮质醇节律的平均水平升高，褪黑素夜间分泌有选择性受损。此外，与年轻对照者相比，老年受试者对地塞米松抑制试验的敏感性降低。这些变化与年龄相关，可能取决于中枢神经系统的改变或激素代谢清除的改变。
