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; Department of Physiology, Chengdu Medical College, Chengdu, Sichuan, 610500, PR China.
J Therm Biol. 2019 Jul;83:87-94. doi: 10.1016/j.jtherbio.2019.05.020. Epub 2019 May 21.
Both warm- and cold-sensitive neurons are found in the lateral parabrachial nucleus (LPB), a crucial relay for skin temperature information from the spinal cord to the preoptic area. The aims of this study were to investigate the electrophysiological properties of temperature-sensitive and -insensitive neurons in brain slices, and elucidate the basic mechanisms underlying the thermosensitivity of rat LPB neurons. In warm-sensitive neurons, temperature exerted no significant effects on resting membrane potential (RMP), threshold potential, and amplitude of the afterhyperpolarizing potential. However, warming significantly increased the prepotential rates of depolarization and the inactivation rates of potassium A current (I) in warm-sensitive neurons, which in turn shortened their interspike interval and elevated the firing rate. In contrast, temperature had no significant effects on the depolarizing prepotentials and inactivation rate of I in temperature-insensitive neurons. Besides, in cold-sensitive neurons, cooling and warming produced membrane depolarization and hyperpolarization, respectively, and there was a strong correlation between firing rate and membrane potential thermosensitivity. Nevertheless, temperature exhibited no significant effect on the depolarizing prepotential of cold-sensitive neurons. These results suggest that LPB neuronal warm sensitivity may reside in the temperature-dependent prepotentials and I, while neuronal cold sensitivity might be mainly due to heat-induced changes in RMP.
冷敏和热敏神经元均存在于外侧臂旁核（LPB）中，该核是脊髓至视前区皮肤温度信息的重要中继站。本研究旨在探讨脑片上温度敏感和不敏感神经元的电生理特性，并阐明大鼠 LPB 神经元热敏性的基本机制。在热敏神经元中，温度对静息膜电位（RMP）、阈电位和后超极化电位幅度没有显著影响。然而，升温显著增加了热敏神经元去极化的预电位率和钾 A 电流（I）的失活率，从而缩短了它们的放电间隔并提高了放电频率。相比之下，温度对不敏感神经元的去极化预电位和 I 的失活率没有显著影响。此外，在冷敏神经元中，冷却和升温分别产生膜去极化和超极化，并且放电频率与膜电位热敏性之间存在很强的相关性。然而，温度对冷敏神经元的去极化预电位没有显著影响。这些结果表明，LPB 神经元的温敏性可能存在于温度依赖性的预电位和 I 中，而神经元的冷敏性可能主要归因于 RMP 引起的热变化。
