Marder E, Eisen J S
J Neurophysiol. 1984 Jun;51(6):1345-61. doi: 10.1152/jn.1984.51.6.1345.
The neurotransmitters mediating the synaptic interactions among the neurons of the pyloric system of the stomatogastric ganglion (STG) of the lobster, Panulirus interruptus, were examined using a combination of electrophysiological, pharmacological, and biochemical techniques. Iontophoretically applied L-glutamate inhibited all motor neurons of the pyloric system. This inhibitory response was blocked by low concentrations of picrotoxin but unaffected by atropine. The anterior burster (AB) interneuron, pyloric dilator (PD) motor neurons, and ventricular dilator (VD) motor neuron were depolarized and excited by iontophoretically applied acetylcholine (ACh). The lateral pyloric (LP) and pyloric (PY) constrictor motor neurons were inhibited by ACh and by the cholinergic agonist, carbachol. These inhibitory cholinergic responses were blocked by atropine but not by picrotoxin. The inhibitory postsynaptic potentials (IPSPs) evoked by the constrictor motor neurons were blocked by picrotoxin but not by atropine. Taken together with previously published data (15, 18), this suggests that the constrictor motor neurons release glutamate at both their excitatory neuromuscular junctions and their inhibitory intraganglionic junctions. The lucifer yellow photoinactivation technique (27) was used to study separately the neurotransmitters released by the electrically coupled PD and AB neurons. The AB-evoked IPSPs were blocked by picrotoxin but not by atropine. The PD-evoked IPSPs were blocked by atropine and other muscarinic antagonists but not by picrotoxin. Somata of PD neurons contained choline acetyltransferase (CAT) activity, but somata of AB neurons contained no detectable CAT activity. On the basis of the data in this paper and previously published data (17, 18), we conclude that the PD neurons release ACh at both their excitatory neuromuscular junctions and their inhibitory intraganglionic connections. Although the AB neuron is electrically coupled to the PD neurons, the AB neuron is not cholinergic. Glutamate is a likely transmitter candidate for the AB neuron. These data show that electrically coupled neurons can release different transmitters. Furthermore, these data show that an IPSP can be the result of the combined actions of two different neurotransmitters, each released from a different neuron. The functional consequences of these conclusions are explored in the following papers (9, 22).
运用电生理学、药理学和生物化学技术相结合的方法，对中断沟龙虾（Panulirus interruptus）口胃神经节（STG）幽门系统神经元间的突触相互作用所涉及的神经递质进行了研究。离子电泳施加的L - 谷氨酸抑制了幽门系统的所有运动神经元。这种抑制反应可被低浓度的苦味毒阻断，但不受阿托品影响。离子电泳施加乙酰胆碱（ACh）可使前爆发神经元（AB）中间神经元、幽门扩张肌（PD）运动神经元和心室扩张肌（VD）运动神经元去极化并兴奋。外侧幽门（LP）和幽门（PY）收缩肌运动神经元受到ACh和胆碱能激动剂卡巴胆碱的抑制。这些抑制性胆碱能反应可被阿托品阻断，但不能被苦味毒阻断。收缩肌运动神经元诱发的抑制性突触后电位（IPSPs）可被苦味毒阻断，但不能被阿托品阻断。结合先前发表的数据（15, 18），这表明收缩肌运动神经元在其兴奋性神经肌肉接头和抑制性神经节内接头处均释放谷氨酸。采用荧光黄光灭活技术（27）分别研究了电耦合的PD和AB神经元释放的神经递质。AB诱发的IPSPs可被苦味毒阻断，但不能被阿托品阻断。PD诱发的IPSPs可被阿托品和其他毒蕈碱拮抗剂阻断，但不能被苦味毒阻断。PD神经元的胞体含有胆碱乙酰转移酶（CAT）活性，但AB神经元的胞体未检测到CAT活性。基于本文数据和先前发表的数据（17, 18），我们得出结论，PD神经元在其兴奋性神经肌肉接头和抑制性神经节内连接中均释放ACh。虽然AB神经元与PD神经元电耦合，但AB神经元不是胆碱能的。谷氨酸可能是AB神经元的神经递质候选物。这些数据表明电耦合神经元可释放不同的神经递质。此外，这些数据表明IPSP可能是两种不同神经递质共同作用的结果，每种神经递质由不同的神经元释放。这些结论的功能后果将在后续论文（9, 22）中探讨。
