Dopamine modulates graded and spike-evoked synaptic inhibition independently at single synapses in pyloric network of lobster
Dopamine modulates graded and spike-evoked synaptic inhibition independently at single synapses in pyloric network of lobster
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DOI：
10.1152/jn.1998.79.4.2063
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发表时间：
1998-04-01
影响因子：
2.5
通讯作者：
Harris-Warrick, RM
中科院分区：
文献类型：
--
作者：
Ayali, A;Johnson, BR;Harris-Warrick, RM
多巴胺（DA）的浴应用程序修改幽门网络产生的有节奏的运动模式在多刺龙虾，Panulirus interruptus的口胃神经节。网络成员之间的突触传递是DA作用的重要目标。所有的幽门神经元都采用分级的递质释放和动作电位介导的突触抑制。DA以前被证明可以改变每个幽门突触的分级突触强度。在这项研究中，我们比较了DA的影响，动作电位介导的和分级的突触抑制在输出突触的外侧幽门（LP）神经元。在每一个突触上，测试的突触后细胞与其他下行和幽门突触输入分离。DA引起的LP尖峰诱发的抑制性突触后电位（IPSPs）在幽门扩张（PD）神经元的大小减少。IPSP大小的变化与DA诱导的突触后PD神经元输入电阻的降低显著线性相关。相反，在用河豚毒素（TTX）灌流口胃神经节（STG）后，在相同的制备物中测试的分级抑制被DA一致地增强。DA使尖峰诱发的IPSP的幅度在与测试的另外两个突触处的突触后细胞输入电阻的改变相同的方向上移动：DA可减弱LP峰电位对心室扩张肌（VD）的抑制作用，降低VD的输入阻力，而增强LP ->幽门收缩肌（PY）突触，增加PY的输入阻力。如前所述，这两个LP输出突触的分级抑制增强。我们的结论是，DA可以差异调制的中央模式发生器网络的成员之间的尖峰诱发和分级组件的突触。在我们研究的突触中，对突触前细胞的作用在分级传递的调制中占主导地位，而对突触后细胞的作用在棘波诱发的IPSP的调节中占主导地位。
Bath application of dopamine (DA) modifies the rhythmic motor pattern generated by the pyloric network in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus. Synaptic transmission between network members is an important target of DA action. All pyloric neurons employ both graded transmitter release and action-potential-mediated synaptic inhibition. DA was previously shown to alter the graded synaptic strength of every pyloric synapse. In this study, we compared DA's effects on action-potential-mediated and graded synaptic inhibition at output synapses of the lateral pyloric (LP) neuron. At each synapse the postsynaptic cell tested was isolated from other descending and pyloric synaptic inputs. DA caused a reduction in the size of the LP spike-evoked inhibitory postsynaptic potentials (IPSPs) in the pyloric dilator (PD) neuron. The change in IPSP size was significantly and linearly correlated with DA-induced reduction in the input resistance of the postsynaptic PD neuron. In contrast, graded inhibition, tested in the same preparations after superfusing the stomatogastric ganglion (STG) with tetrodotoxin (TTX), was consistently enhanced by DA. DA shifted the amplitude of spike-evoked IPSPs in the same direction as the alteration of the postsynaptic cell input resistance at two additional synapses tested: DA weakened the LP spike-mediated inhibition of the ventricular dilator (VD) and reduced the VD input resistance, while strengthening the LP --> pyloric constrictor (PY) synapse and increasing PY input resistance. As previously reported, graded inhibition was enhanced at these two LP output synapses. We conclude that DA can differentially modulate the spike-evoked and graded components of synapses between members of a central pattern generator network. At the synapses we studied, actions on the presynaptic cell predominate in the modulation of graded transmission, whereas effects on postsynaptic cells predominate in the regulation of spike-evoked IPSPs.