Costa E J, Lopes R H, Lamy-Freund M T
Instituto de Física, Universidade de São Paulo, Brazil.
J Pineal Res. 1995 Oct;19(3):123-6. doi: 10.1111/j.1600-079x.1995.tb00180.x.
Melatonin, the chief hormone of the pineal gland, has been reported to interact with a variety of different cells. This ubiquitously acting hormone has been found to interact with protein receptors both at the cell membrane and in the nucleus. Moreover, melatonin was recently shown to be a very potent hydroxyl radical scavenger. The present work focuses on the interaction of melatonin with pure lipid bilayers. It is shown that melatonin can cross multilamellar lipid vesicles, which are used here as model systems for the lipid phase of biological membranes. Thus, the data prove that melatonin can easily pass through the cell membrane and bath every part of the cell, as previously suggested in the literature. Melatonin lipid association constant was calculated based on the change of the hormone fluorescence intensity due to its penetration into the hydrophobic lipid phase. Though melatonin was recently shown to be highly soluble in aqueous media, its lipid association constant is rather high, indicating that the biological action of the hormone is likely to be at the membrane level, either via its interaction with membrane receptors, and/or as a lipoperoxidation radical scavenger.
褪黑素是松果体的主要激素，据报道它能与多种不同细胞相互作用。这种具有广泛作用的激素已被发现可与细胞膜和细胞核中的蛋白质受体相互作用。此外，褪黑素最近被证明是一种非常有效的羟自由基清除剂。目前的工作重点是褪黑素与纯脂质双层的相互作用。结果表明，褪黑素可以穿过多层脂质囊泡，这里将其用作生物膜脂质相的模型系统。因此，数据证明褪黑素可以轻松穿过细胞膜并作用于细胞的各个部分，正如之前文献中所提出的那样。基于褪黑素渗透到疏水脂质相导致的激素荧光强度变化，计算了褪黑素的脂质结合常数。尽管褪黑素最近被证明在水性介质中高度可溶，但其脂质结合常数相当高，这表明该激素的生物学作用可能在膜水平，要么通过与膜受体相互作用，和/或作为脂质过氧化自由基清除剂。
