Antonov I, Chang S, Zakharenko S, Popov S V
Department of Physiology and Biophysics, University of Illinois at Chicago, 60612, USA.
Neuroscience. 1999 Mar;90(3):975-84. doi: 10.1016/s0306-4522(98)00497-7.
Neurotransmitter secretion from the nerve terminal is mediated by the fusion of synaptic vesicles with the plasma membrane. It is generally believed that neurotransmitter release in mature synapses is localized to the presynaptic nerve terminals. To probe the topology of neurotransmitter secretion along developing axons in culture, we recorded membrane currents from myocytes manipulated into contact with axons. At the early stages of growth, exocytotic events were detected along the axon as well as at the growth cone. At the later stages of growth, neurotransmitter secretion adopted the form of a smooth proximodistal gradient, with the highest level of activity at the growth cone region. Our results reveal the existence of a previously undetected early stage of axonal growth and suggest developmental regulation in the pattern of neurotransmitter secretion along the growing nerve processes.
神经递质从神经末梢的分泌是由突触小泡与质膜融合介导的。一般认为，成熟突触中的神经递质释放局限于突触前神经末梢。为了探究培养中发育轴突上神经递质分泌的拓扑结构，我们记录了与轴突接触的肌细胞的膜电流。在生长的早期阶段，沿轴突以及生长锥都检测到了胞吐事件。在生长的后期阶段，神经递质分泌呈现出一种平滑的近端到远端的梯度形式，生长锥区域的活性水平最高。我们的结果揭示了轴突生长早期阶段的存在，此前未被发现，并表明在沿生长神经突起的神经递质分泌模式中存在发育调控。
