Stanley E F
J Neurosci. 1984 Jul;4(7):1904-11. doi: 10.1523/JNEUROSCI.04-07-01904.1984.
Although the giant synapse in the squid stellate ganglion has served as a model in the understanding of the ionic and electrical changes that occur during the release of transmitter from nerve terminals, little is known about the pharmacology of this synapse or the identity of its neurotransmitter. In the present study, the suggestion that acetylcholine (ACh) is the excitatory transmitter at this synapse was tested by exploring the actions of cholinergic agents on the pre- and postsynaptic giant axons and on the excitatory postsynaptic potential (EPSP). A novel arterial perfusion technique that circumvents the diffusion barrier from the bathing medium to the synapse has been used to demonstrate a depolarizing action of ACh and its agonist carbachol on the post- but not the presynaptic axon. The cholinergic receptors are distinct from receptors activated by amino acids, such as glutamate, have a reversal potential of about -48 mV, are anion-permeable, and desensitize without blocking the EPSP. It is concluded that these receptors are involved in an inhibitory input onto the postsynaptic giant axon and, therefore, that ACh is most probably not the transmitter at the squid giant synapse.
尽管鱿鱼星状神经节中的巨大突触一直是理解神经末梢释放递质过程中发生的离子和电变化的模型，但对于该突触的药理学或其神经递质的身份却知之甚少。在本研究中，通过探究胆碱能药物对突触前和突触后巨大轴突以及兴奋性突触后电位（EPSP）的作用，来检验乙酰胆碱（ACh）是该突触兴奋性递质这一假说。一种新颖的动脉灌注技术绕过了从浴液介质到突触的扩散屏障，已被用于证明ACh及其激动剂卡巴胆碱对突触后而非突触前轴突具有去极化作用。胆碱能受体与由氨基酸（如谷氨酸）激活的受体不同，其反转电位约为 -48 mV，是阴离子通透的，并且在不阻断EPSP的情况下脱敏。得出的结论是，这些受体参与了对突触后巨大轴突的抑制性输入，因此，ACh很可能不是鱿鱼巨大突触的递质。
