Xue Yawen, Yang Yonglu, Tang Yu, Ye Mengping, Xu Jianhui, Zeng Yixin, Zhang Jie
Department of Physiology, Chengdu Medical College, Chengdu, Sichuan 610500, PR China; Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Chengdu Medical College, Chengdu, Sichuan 610500, PR China.
Key Laboratory of Thermoregulation and Inflammation of Sichuan Higher Education Institutes, Chengdu Medical College, Chengdu, Sichuan 610500, PR China.
Neurosci Lett. 2016 Apr 21;619:15-20. doi: 10.1016/j.neulet.2016.02.058. Epub 2016 Mar 2.
The lateral parabrachial (LPB) neurons play a pivotal role in the thermoregulatory afferent pathway by transmitting cutaneous thermosensory signals received from spinal neurons directly to the thermoregulatory command center, the preoptic area (POA). The present study was conducted to electrophysiologically characterize the local temperature responsiveness of rat LPB neurons in brain slices to evaluate their local thermosensitivity and permit comparison with thermosensitive neurons in POA and spinal cord slices under consistent experimental conditions. In current clamp, warm- and cold-sensitive neurons were recorded in LPBel, LPBc and LPBd, the three LPB subnuclei responsible for the transmission of cutaneous feedforward signals. Of the 92 spontaneously firing LPB neurons, 27% were warm sensitive, 10% were cold sensitive, and 63% were temperature insensitive, and the spontaneous firing rate of the warm-sensitive neurons was significantly greater than that of the temperature-insensitive neurons. These proportions and spontaneous activity are similar to results obtained in the POA and spinal cord. Furthermore, the thermosensitivity was also present in 38% of silent neurons evoked by injection of a small amount of depolarizing current. Warm-sensitive neurons in the LPB were similar in thermoresponsiveness to those in the POA and spinal cord. However, cold sensitivity in the LPB was distinct from that in the POA. The firing rate of most cold-sensitive neurons changed steeply at a relatively narrow band of temperature, and some of them were silent near thermoneutrality. The percentages of thermosensitive and insensitive neurons within the three LPB subnuclei were not significantly different, nor were the mean maximal thermal coefficients of the thermosensitive neurons. These results suggest that LPB have local thermosensory functions as POA and spinal cord, and might be an important extrahypothalamic "thermoregulator".
外侧臂旁核（LPB）神经元在体温调节传入通路中起着关键作用，它将从脊髓神经元接收的皮肤温度感觉信号直接传递到体温调节指挥中心——视前区（POA）。本研究旨在通过电生理学方法表征脑片中大鼠LPB神经元的局部温度反应性，以评估其局部热敏性，并在一致的实验条件下与POA和脊髓切片中的热敏神经元进行比较。在电流钳记录中，在负责皮肤前馈信号传递的三个LPB亚核LPBel、LPBc和LPBd中记录到了对温热和冷敏感的神经元。在92个自发放电的LPB神经元中，27%对温热敏感，10%对冷敏感，63%对温度不敏感，且温热敏感神经元的自发放电率显著高于温度不敏感神经元。这些比例和自发活动与在POA和脊髓中获得的结果相似。此外，在注入少量去极化电流诱发的38%的静息神经元中也存在热敏性。LPB中的温热敏感神经元在温度反应性方面与POA和脊髓中的相似。然而，LPB中的冷敏感性与POA中的不同。大多数冷敏感神经元的放电率在相对较窄的温度范围内急剧变化，其中一些在体温中性附近处于静息状态。三个LPB亚核内热敏和不敏感神经元的百分比没有显著差异，热敏神经元的平均最大热系数也没有显著差异。这些结果表明，LPB与POA和脊髓一样具有局部温度感觉功能，可能是一个重要的下丘脑外“体温调节者”。
