Temperature sensitivity of graded synaptic transmission in the lobster stomatogastric ganglion.
Temperature sensitivity of graded synaptic transmission in the lobster stomatogastric ganglion.
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发表时间：
1991-03
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通讯作者：
B. Johnson;Jack Peck;R. Harris-Warrick
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作者：
B. Johnson;Jack Peck;R. Harris-Warrick
我们研究了龙虾口胃神经节幽门回路中梯度化学突触强度的温度敏感性。从20.4摄氏度冷却到11.3摄氏度，所有六个幽门突触的梯度突触电位（GSP）幅度都降低了。冷却似乎降低了其中三个突触的输入-输出曲线线性部分的斜率，并且没有显著改变任何突触的递质释放阈值。在16.5℃时，具有突触前幽门扩张（PD）细胞的神经元对表现出突触强度的递减，而具有突触前幽门外侧（LP）或腹侧扩张（VD）细胞的神经元对则没有。由输入电阻、动作电位振幅和电耦合测量确定，冷却时，广义的输入电阻减小不是导致GSP振幅减小的原因。我们得出结论，冷却通过直接的突触作用降低了渐变的化学强度。由于PD和VD细胞使用相同的递质并作用于一些相同的突触后细胞，它们对冷却的不同敏感性进一步表明作用于突触前部位。我们实验中使用的温度范围包括动物在自然界中通常遇到的温度范围。因此，产生幽门运动节律的分级突触相互作用的相对重要性可能随着温度的短暂变化而变化。
We examined the temperature sensitivity of graded chemical synaptic strength within the pyloric circuit of the spiny lobster stomatogastric ganglion. Cooling from 20.4 degrees C to 11.3 degrees C reduced the graded synaptic potential (GSP) amplitude at all six pyloric synapses tested. Cooling appeared to reduce the slope of the linear part of the input-output curve at three of these synapses, and did not significantly alter the threshold for transmitter release at any synapses. Pairs of neurons with a presynaptic pyloric dilator (PD) cell showed reductions in graded synaptic strength at 16.5 degrees C but those with presynaptic lateral pyloric (LP) or ventral dilator (VD) cells did not. A generalized decrease in input resistance is not responsible for the reduced GSP amplitude upon cooling, as determined by input resistance, action potential amplitude and electrical coupling measurements. We conclude that cooling reduces graded chemical strength by a direct synaptic action. Since the PD and VD cells use the same transmitter and act on some of the same postsynaptic cells, their differential sensitivity to cooling further suggests a presynaptic site of action. The temperature range used in our experiments encompasses the range that the animal normally encounters in nature. Thus, the relative importance of graded synaptic interactions in generating the pyloric motor rhythm may vary with transient changes in temperature.