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

1.在麻醉大鼠的腰骶段，背角细胞对阴囊皮肤温度的无害范围（10-40 ℃）内的温度变化做出反应，进行细胞外记录。将温度响应背角细胞（65）分为两组：显示出通过皮肤加温而放电率增加的温响应细胞（48），温响应，和显示出通过皮肤冷却而放电率增加的冷响应细胞（17），冷响应。研究了电刺激中缝大核（NRM）和蓝斑下核（SC）对其放电活动的影响.在NRM以及在SC中的电刺激的效果被认为是其特征在于部分或完全抑郁症的温暖或寒冷的反应。背景活动基本保持不受影响。大部分（95%）的温反应细胞受到NRM刺激后温度反应降低，而大部分（79%）的冷反应细胞受到SC刺激后温度反应降低.在四个温反应细胞中，NRM引起的温度反应的抑制被5-羟色胺拮抗剂Methysergide（1 mg/kg，i. v.）部分拮抗。这种NRM诱发的抑制被认为是由多巴胺能中缝-脊髓通路介导的。结果表明，中缝和subcoeruleo脊髓通路下行调制脊髓传递的温暖和寒冷的信号，有助于中央温度调节。

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.