Division of Medical Sciences and Department of Biology, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada.
Eur J Neurosci. 2010 Mar;31(5):797-807. doi: 10.1111/j.1460-9568.2010.07132.x.
Although it is accepted that new neurons continue to be generated in the hippocampal dentate gyrus (DG) throughout adulthood, it has recently become apparent that this process is not homogeneous, and that a small region of the DG lacks neurogenesis. Here, we show that the relative area of this neurogenesis quiescent zone (NQZ) did not vary after the peak in hippocampal postnatal neurogenesis and until animals reached adulthood, although the ratio between its actual volume and the total volume of the DG doubled during this time. However, we were able to identify a few mitotic cells that reside within this subregion in early adolescent rats. Furthermore, these cells can be activated, and 1 week of voluntary exercise was enough to significantly increase the number of mitotic cells within the NQZ of adolescent rats. There was, however, no corresponding increase in the number of new neurons in this subregion of the DG, suggesting that some factor necessary to allow these cells to develop into a mature phenotype is missing. Moreover, the same intervention was ineffective in increasing either proliferation or neurogenesis in older adult rats. Surprisingly, we found no evidence for the existence of an NQZ in the mouse DG, suggesting that the neurogenic process in these two rodent species is differently regulated. Understanding the molecular mechanisms underlying the existence of the NQZ in the rat DG might shed light on the processes that regulate adult neurogenesis and its modulation by factors such as aging and exercise.
虽然人们普遍认为成年后海马齿状回（DG）中仍会不断产生新神经元，但最近显然发现这一过程并非同质的，DG 的一小部分区域缺乏神经发生。在这里，我们发现，神经发生静止区（NQZ）的相对区域在海马体出生后神经发生的高峰期后并没有变化，直到动物成年，尽管在此期间，它的实际体积与 DG 的总体积之间的比例增加了一倍。然而，我们能够在早期青春期大鼠中识别出存在于该亚区的少数有丝分裂细胞。此外，这些细胞可以被激活，并且 1 周的自愿运动足以显著增加青春期大鼠 NQZ 中的有丝分裂细胞数量。然而，在 DG 的这个亚区中，新神经元的数量并没有相应增加，这表明存在某种必需的因素，使其能够发育成成熟表型。此外，同样的干预措施在增加老年成年大鼠的增殖或神经发生方面没有效果。令人惊讶的是，我们在小鼠 DG 中没有发现 NQZ 存在的证据，这表明这两种啮齿动物的神经发生过程受到不同的调控。了解 NQZ 在大鼠 DG 中存在的分子机制可能有助于阐明调节成年神经发生及其被衰老和运动等因素调节的过程。
