Dean J B, Boulant J A
Department of Physiology, College of Medicine, Ohio State University, Columbus 43210.
Am J Physiol. 1992 Sep;263(3 Pt 2):R679-84. doi: 10.1152/ajpregu.1992.263.3.R679.
Thermoregulatory responses may be delayed in onset and offset by several minutes after changes in hypothalamic temperature. Our preceding study found neurons that displayed delayed firing rate responses during clamped thermal stimulation in remote regions of rat diencephalic tissue slices. The present study looked for similar delayed firing rate responses during clamped (1.5-10 min) changes in each neuron's local temperature. Of 26 neurons tested with clamped thermal stimulation, six (i.e., 23%) showed delayed responses, with on-latencies of 1.0-7.8 min. These neurons rarely showed off-latencies, and the delayed response was not eliminated by synaptic blockade. The on-latencies and ranges of local thermosensitivity were similar to delayed neuronal responses to remote temperature; however, remote-sensitive neurons displayed off-latencies, higher firing rates at 37 degrees C, and greater sensitivity to thermal stimulation. Our findings suggest that delayed thermosensitivity is an intrinsic property of certain neurons and may initiate more elaborate or prolonged delayed responses in synaptically connected diencephalic networks. These networks could explain the delayed thermoregulatory responses observed during hypothalamic thermal stimulation.
在下丘脑温度变化后，体温调节反应的起始和消退可能会延迟几分钟。我们之前的研究发现，在大鼠间脑组织切片的远端区域进行钳制热刺激时，神经元会表现出延迟的放电频率反应。本研究在每个神经元的局部温度进行钳制（1.5 - 10分钟）变化期间，寻找类似的延迟放电频率反应。在用钳制热刺激测试的26个神经元中，6个（即23%）表现出延迟反应，起始潜伏期为1.0 - 7.8分钟。这些神经元很少表现出消退潜伏期，并且突触阻断并未消除延迟反应。局部热敏感性的起始潜伏期和范围与对远端温度的延迟神经元反应相似；然而，对远端温度敏感的神经元表现出消退潜伏期、在37摄氏度时具有更高的放电频率，并且对热刺激更敏感。我们的研究结果表明，延迟热敏感性是某些神经元的固有特性，并且可能在突触连接的间脑网络中引发更复杂或持久的延迟反应。这些网络可以解释在下丘脑热刺激期间观察到的延迟体温调节反应。
