Segal M, Koester J
Brain Res. 1980 Oct 20;199(2):459-65. doi: 10.1016/0006-8993(80)90704-0.
We have investigated neurons that receive inputs from more than one cholinergic interneuron, to see whether one cholinergic input can depolarize and the other hyperpolarize by virtue of activating different ACh receptors. We have examined synapses made in the abdominal ganglion of Aplysia californica by 3 cholinergic interneurons. Two of those interneurons have previously been shown to be cholinergic. Using both biochemical and pharmacological tests we have shown a third interneuron to be cholinergic. For 7 postsynaptic cells, we compared 6 new connections that we have identified from cholinergic interneurons, and 12 previously known connections. In each case we found that different cholinergic inputs onto any given cell produced the same synaptic action. This finding held even for L7, a cell known to have two types of ACh receptors. These data are consistent with the hypothesis that a postsynaptic cell does not segregate different types of ACh receptors. If generally true, this lack of segregation may help explain why a nervous system uses more than one neurotransmitter as well as why certain interneurons are needed in neural networks.
我们研究了从不止一个胆碱能中间神经元接收输入的神经元，以观察一个胆碱能输入是否能通过激活不同的乙酰胆碱受体而使膜电位去极化，而另一个则使其超极化。我们检查了加州海兔腹神经节中由3个胆碱能中间神经元形成的突触。其中两个中间神经元先前已被证明是胆碱能的。通过生化和药理学测试，我们证明了第三个中间神经元也是胆碱能的。对于7个突触后细胞，我们比较了从胆碱能中间神经元中识别出的6个新连接和12个先前已知的连接。在每种情况下，我们发现任何给定细胞上不同的胆碱能输入都会产生相同的突触作用。这一发现甚至适用于L7，一个已知具有两种乙酰胆碱受体类型的细胞。这些数据与突触后细胞不会分离不同类型乙酰胆碱受体的假设一致。如果这一情况普遍成立，这种缺乏分离的现象可能有助于解释为什么神经系统会使用不止一种神经递质，以及为什么神经网络中需要某些中间神经元。
