Maestroni G J, Conti A, Pierpaoli W
Istituto Cantonale di Patologia, Locarno, Switzerland.
Clin Exp Immunol. 1987 May;68(2):384-91.
The pineal gland constitutes a major neuroendocrine organ in the brain. It transduces exogenous signals such as circadian and seasonal variations of light and temperature into proper hormonal changes which adjust and adapt internal endocrine functions. These pineal activities seem to be exerted via circadian synthesis and release of the indoleamine melatonin, a neurohormone secreted by the pineal itself. Alteration of circadian rhythms have been associated with affective disorders, psychosomatic diseases, cancer and many other pathologies. We have reported that functional and pharmacologic inhibition of melatonin synthesis results in depressed immune functions in vivo and that exogenous, evening administration of melatonin enhances antibody formation via an antigen-activated process and also antagonizes the immunosuppressive effects of corticosterone. We communicate here findings demonstrating that (a) three different inbred strains of mice possess a clear-cut cycle of melatonin levels in serum, (b) that melatonin administered in the evening enhances primary antibody response (IgM and IgG immunoglobulins) in vivo according to a dose-response behaviour and that (c) the opioid receptors blocker naltrexone antagonizes the immunostimulatory effect of melatonin. These findings point to a fundamental immunoregulatory role of circadian melatonin and to an activity of the neurohormone via opioid peptides.
松果体是大脑中的一个主要神经内分泌器官。它将诸如昼夜节律以及光照和温度的季节性变化等外源性信号转化为适当的激素变化，从而调节和适应内部内分泌功能。这些松果体活动似乎是通过昼夜节律性合成和释放吲哚胺褪黑素（一种由松果体自身分泌的神经激素）来实现的。昼夜节律的改变与情感障碍、身心疾病、癌症及许多其他病症有关。我们曾报道，褪黑素合成的功能抑制和药物抑制会导致体内免疫功能低下，而在傍晚给予外源性褪黑素可通过抗原激活过程增强抗体形成，并且还能拮抗皮质酮的免疫抑制作用。我们在此报告的研究结果表明：（a）三种不同的近交系小鼠血清中褪黑素水平具有明确的周期；（b）傍晚给予褪黑素可根据剂量反应行为增强体内的初次抗体反应（IgM和IgG免疫球蛋白）；（c）阿片受体阻滞剂纳曲酮可拮抗褪黑素的免疫刺激作用。这些研究结果表明昼夜节律性褪黑素具有重要的免疫调节作用，并且该神经激素通过阿片肽发挥作用。
