Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada.
Trends Neurosci. 2011 Aug;34(8):393-400. doi: 10.1016/j.tins.2011.06.004. Epub 2011 Jul 7.
Axons have evolved to acquire myelination, enabling denser packing and speedier transmission. Although myelin is considered a passive insulator, recent reports suggest a more dynamic role. Axons, in turn, are endowed with neurotransmitter release and uptake systems along their trunks. Based on these observations, I argue that there may exist a new type of chemical synapse between axon and myelin, one that supports activity-dependent communication between the two. This raises intriguing possibilities of dynamic fine-tuning of the myelin sheath even in adulthood, efficient recruitment of resources for myelin maintenance and bi-directional signaling, whereby the axon informs its myelinating cell of its metabolic needs proportionally to the electrical traffic it is transmitting. This would also have implications for de- and dysmyelinating diseases should this axo-myelinic synapse become dysfunctional.
轴突已经进化到可以获得髓鞘，从而实现更密集的包装和更快的传输。虽然髓鞘被认为是一种被动的绝缘体，但最近的报告表明它具有更具动态性的作用。反过来，轴突在其干上配备了神经递质释放和摄取系统。基于这些观察，我认为在轴突和髓鞘之间可能存在一种新型的化学突触，它支持两者之间的活动依赖性通信。这就提出了一种有趣的可能性，即在成年期，髓鞘鞘可以进行动态微调，有效地为髓鞘维持和双向信号传递募集资源，从而使轴突根据其传输的电流量向其髓鞘形成细胞告知其代谢需求。如果这种轴突-髓鞘突触失去功能，这也将对脱髓鞘和髓鞘异常疾病产生影响。
