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

1.在乌拉坦麻醉大鼠的阴囊皮肤温度的无害范围内(10-40ﾟ℃)，对背角细胞进行细胞外记录。温度反应的背角细胞(65个)分为两组：温敏反应细胞(48个)和冷反应细胞(17个)，温敏反应细胞(48个)通过皮肤温暖反应增加放电频率，冷反应细胞(17个)通过皮肤咕咕叫冷反应增加放电频率。方法：1.研究电刺激中缝大核(NRM)和蓝斑下核(SC)对其放电活动的影响。电刺激NRM和SC的效应被发现表现为部分或完全抑制热或冷反应。背景活动基本不受影响。大部分(95%)温敏细胞在刺激NRM时温度反应减弱，而大多数(79%)冷反应细胞在SC刺激下温度反应减弱。在4个温应性细胞中，5-羟色胺拮抗剂甲基丝氨酸(1 mg/kg)静脉注射可部分拮抗NRM引起的体温反应抑制。这种NRM诱发的抑郁被认为是由5-羟色胺能中缝脊髓通路介导的。这些结果表明，中缝和蓝髓下脊髓通路下行调制了有助于中枢体温调节的冷暖信号在脊髓中的传递。

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.