Golding D W
Biomedical EM Unit, University of Newcastle upon Tyne, UK.
Bioessays. 1994 Jul;16(7):503-8. doi: 10.1002/bies.950160710.
Neurons are now known to produce a variety of types of chemical transmitters. Classical transmitters are stored within synaptic vesicles which undergo synaptic exocytosis in association with presynaptic thickenings. The larger, dense-cored secretory granules present in most neurons contain neuropeptides and mainly discharge their contents at morphologically undifferentiated (i.e. nonsynaptic) sites. The synaptic character of vesicle discharge enables transmitters to exercise a highly focal action, whereas nonsynaptic release probably relates to the slow rate of degradation of many neuropeptides and their consequent widespread diffusion and sphere of action. However, one variant of the basic pattern, involving the restriction of granule discharge to areas of the terminal plasmalemma situated adjacent to the postsynaptic cells (i.e. a parasynaptic configuration), enables a degree of targeted peptide discharge to be achieved. The diversity of patterns of neural exocytosis adds a further dimension to the complexity of nervous function.
现在已知神经元会产生多种类型的化学递质。经典递质储存在突触小泡中，这些小泡会与突触前增厚处一起经历突触胞吐作用。大多数神经元中存在的较大的、有致密核心的分泌颗粒含有神经肽，并且主要在形态上未分化（即非突触）的部位释放其内容物。小泡释放的突触特性使递质能够发挥高度局部化的作用，而非突触释放可能与许多神经肽的缓慢降解速率及其随后的广泛扩散和作用范围有关。然而，基本模式的一种变体，即颗粒释放局限于终末质膜与突触后细胞相邻的区域（即旁突触结构），能够实现一定程度的靶向肽释放。神经胞吐模式的多样性为神经功能的复杂性增添了新的维度。
