Mechanisms of thermoreception on isolated hypothalamic neurons.

用“全细胞”构型研究了大鼠视前区和下丘脑前区(PO/AH)分离细胞的离子电流对温度的反应。大多数记录到的神经元在升温期间(32~40ﾟC)表现出非失活内向电流的线性增加，Q_&lt；10&gt；约为2。这种电流主要是由Na~+内流引起的，因为当外液中胆碱取代一半Na~+时，内向电流减少了一半。另一方面，约有24%的PO/AH神经元对加温明显敏感，在高温区(35-40ﾟ℃)，非内向电流对温度升高有较高的Q_(10)。河豚毒素(TTX)可逆地阻断高温范围内电流的这种增加。Q_lt；10&gt；为2的神经元内向电流不受河豚毒素的影响。结果表明，PO/AH内的部分神经元具有非失活的钠通道，该通道在高温区高度敏感。这些神经元应该是“主要的”温敏性神经元，它是大脑中的温度计。

The ionic current responses to temperature of dissociated cells from the preoptic and anterior hypothalamus (PO/AH) of rat were investigated, using the 'whole-cell' configuration. The majority of the recorded neurons showed a linear increase in a non-inactivating inward current during warming (32 to 40ﾟC), and the Q_<10> was about 2. This current is mainly caused by Na^+-influx because the inward current was reduced by half when external solution was substituted choline for half of Na^+. On the other hand, about 24% of PO/AH neurons were markedly sensitive to warming and the increase in non-inactivating inward current to a rise in temperature in hyperthermic range (35-40ﾟC) had a high Q_<10> (4.3-7.0). This increase in current in the hyperthermic range was reversibly blocked by tetrodotoxin (TTX). The inward current in neurons with a Q_<10> of 2 was not affected by TTX. The results show that some neurons in the PO/AH possess a non-inactivating sodium channel that is highly temperature-sensitive in the hyperthermic range. These neurons should be the 'primary' warm-sensitive neurons which are thermometer in the brain.