Rebuffat P, Mazzocchi G, Gottardo G, Coi A, Meneghelli V, Nussdorfer G G
J Submicrosc Cytol. 1987 Jul;19(3):415-21.
The effects of a long-term administration of melatonin on the adrenal zona fasciculata were investigated both in 'normal' rats and in animals whose hypothalamo-hypophyseal-adrenal axis had been interrupted by a prolonged infusion with dexamethasone or dexamethasone plus maintenance doses of ACTH. In the 'normal' rats, melatonin caused a notable atrophy of zona fasciculata cells, coupled with a significant lowering in the plasma concentration of corticosterone. On the contrary, in dexamethasone- or dexamethasone plus ACTH-infused animals, melatonin induced an evident hypertrophy of zona fasciculata cells which, however, was not associated with a rise in the corticosterone blood level. The hypothesis is advanced that the direct stimulatory effect of melatonin on the growth of zona fasciculata in 'normal' rats can be masked by the concurrent inhibition of the hypophyseal release of ACTH. The possible mechanism of the direct effect of melatonin on the zona fasciculata is discussed in the light of evidence indicating that this hormone enhances the intracellular catabolism of corticosterone, which is well-known to exert a powerful direct depression of the growth and steroidogenic capacity of rat adrenocortical cells.
研究了长期给予褪黑素对“正常”大鼠以及下丘脑 - 垂体 - 肾上腺轴已被地塞米松或地塞米松加维持剂量促肾上腺皮质激素（ACTH）长期输注中断的动物肾上腺束状带的影响。在“正常”大鼠中，褪黑素导致束状带细胞明显萎缩，同时血浆皮质酮浓度显著降低。相反，在地塞米松或地塞米松加ACTH输注的动物中，褪黑素诱导束状带细胞明显肥大，然而，这与血液中皮质酮水平升高无关。有人提出假说，褪黑素对“正常”大鼠束状带生长的直接刺激作用可能被同时抑制垂体ACTH释放所掩盖。根据表明该激素增强皮质酮细胞内分解代谢的证据，讨论了褪黑素对束状带直接作用的可能机制，众所周知，皮质酮对大鼠肾上腺皮质细胞的生长和类固醇生成能力有强大的直接抑制作用。
