Study on the modulation of temperature signals from the skin by the nucleus raphe magnus and subcoeruleus

1. 研究了氨基甲酸乙酯麻醉大鼠腰骶段阴囊皮肤温度在10 ~ 40℃范围内对温度变化的响应。对温度有反应的背角细胞（65）被分为两组：对温度有反应的细胞（48），在皮肤变暖、变暖反应时放电速率增加；对温度有反应的细胞（17），在皮肤变冷、变冷反应时放电速率增加。研究了电刺激中缝大核（NRM）和蓝下核（SC）对其放电活动的影响。电刺激对NRM和SC的影响表现为部分或完全抑制热反应或冷反应。背景活动基本上没有受到影响。大多数（95%）热反应细胞在NRM刺激下温度反应下降，而大多数（79%）冷反应细胞在SC刺激下温度反应下降。在4个热反应细胞中，5 -羟色胺拮抗剂Methysergide （1 mg/kg，静脉注射）可部分拮抗nrm引起的温度反应抑制。nrm诱发的抑郁可能是由5 -羟色胺能脊髓通路介导的。结果表明，中缝和蓝下通路下行调节脊髓的冷热信号传递，有助于中枢体温调节。

1. Extracellular recordings were made from dorsal horn cells responsive to temperature changes in the innocuous range (10-40ﾟC) of scrotal skin temperature in the lumbosacral segment of urethane-anesthetized rats. The temperature responsive dorsal horn cells (65) were classified into two groups : warm-responsive cells (48) showing an increase in firing rate by skin warming, warm-response, and cold-responsive cells (17) showing an increase in firing rate by skin cooing, cold-response. The effects of electrical stimulation in the nucleus raphe magnus (NRM) and subcoeruleus (SC) on their firing activity were studied.2. Effect of electrical stimulation in the NRM as well as in the SC was found to be characterized by a partial or complete depression of warm- or cold-responses. The background activity mostly remained unaffected.3. Depression of temperature response occurred in most (95%) of warm-responsive cells by NRM stimulation, whereas in the majority (79%) of cold-responsive cells by SC stimulation.4. In four warm-responsive cells, NRM-evoked depression of their temperature responses was partially antagonized by Serotonin antagonist, Methysergide (1 mg/kg, i.v.). Such NRM-evoked depression was suggested to be mediated by serotonergic raphe-spinal pathways.5. The results suggest that the raphe- and subcoeruleo-spinal pathways descendingly modulate the spinal transmission of warm and cold signals contributing to central thermoregulation.