Institute of Neuroscience, Carleton University, Ottawa, ON, Canada.
J Pineal Res. 2009 Nov;47(4):313-7. doi: 10.1111/j.1600-079X.2009.00716.x. Epub 2009 Oct 1.
It was previously shown that pinealectomy causes delayed loss of pyramidal neurons in rat hippocampal layers CA1/3 and that this is reversed by melatonin supplementation. Here, we used immunohistologic detection of doublecortin, a protein expressed in newborn neurons, to determine if melatonin supplementation promotes neurogenesis after pinealectomy. It was found that melatonin supplementation significantly increased the number of doublecortin immunoreactive neurons in the dentate gyrus over the postsurgical intervals of 2, 4, 6, 8, 10 and 17 months. The increase was most evident at 6 months postsurgery and thereafter, and was apparent despite a severe decline in doublecortin-labeled cells over the 17 month postsurgical interval in all groups of rats. Doublecortin immunoreactive cells were not observed in the pyramidal layer itself. These results indicate that melatonin promotes neurogenesis in the dentate gyrus of pinealectomized rats. However, it is equivocal that these newborn neurons migrate to the pyramidal layer and account for the reappearance of neurons at this location in these rats. This study provides further evidence for a role of melatonin in promoting neurogenesis, adding another role to its already remarkably pleiotropic profile. The scope and significance of this newly discovered role remains to be determined.
先前的研究表明，松果体切除会导致大鼠海马 CA1/3 层锥体神经元的延迟性丧失，而褪黑素的补充可以逆转这种情况。在这里，我们使用双皮质蛋白（一种在新生神经元中表达的蛋白质）的免疫组织化学检测来确定褪黑素补充是否能促进松果体切除后的神经发生。结果发现，褪黑素补充显著增加了术后 2、4、6、8、10 和 17 个月齿状回中双皮质蛋白免疫反应性神经元的数量。在术后 6 个月时增加最为明显，此后，尽管所有大鼠在术后 17 个月时双皮质蛋白标记细胞严重减少，但仍明显增加。在锥体层本身没有观察到双皮质蛋白免疫反应性细胞。这些结果表明，褪黑素促进了松果体切除大鼠齿状回的神经发生。然而，这些新生神经元是否迁移到锥体层，并解释了这些大鼠在该部位神经元再次出现，这一点仍存在争议。这项研究为褪黑素在促进神经发生中的作用提供了进一步的证据，为其已经非常多样化的作用模式增添了另一个作用。这种新发现的作用的范围和意义仍有待确定。
