中文摘要：

本文旨在研究丘脑中央下核（thalamic nucleus submedius，Sm）是否参与持续伤害感受性调制。以自动运动检测系统记录大鼠一侧后爪皮下注射福尔马林诱发的伤害性行为（烦乱反应）为指标，观察电刺激和电解损毁Sm对烦乱反应的效应。结果显示，电刺激（100μA,5min）同侧或对侧Sm明显抑制福尔马林诱发的第二时相的烦乱反应，而刺激Sm外邻近结构（超过0．5mm）对烦乱反应无明显效应。电解损毁双侧Sm对第一或第二时相的烦乱反应均无影响。结果提示，Sm不仅参与急性时相性伤害感受性调制，也参与持续性伤害感受性调制。本研究为Sm参与下行痛调制提供了新的证据。

英文摘要：

The aim of the present study was to examine whether the thalamic nucleus submedius （Sm） was involved in the modulation of persistent nociception. Using an automated movement detection system to measure nociceptive behavior （agitation） induced by subcutaneous injection of formalin into the hind paw pad, the effects of electrical stimulation or electrolytic lesion of the Sm on the agitation response were examined in conscious rats. Unilateral stimulation （100 μA, 5 min） of the Sm ipsilateral or contralateral to the formalin-injected paw produced a significant inhibition of agitation response in the second phase, while stimulation of thalamic structures more than 0.5 mm away from the Sm had no effect on agitation response. Bilaterally electrolytic lesion of the Sm did not significantly influence the number of agitation events induced by formalin injection in the first phase or the second phase. These results suggest that the Sm is not only involved in the modulation of phase nociception, as reported previously, but also of persistent nociception. The present study provides novel evidence for the participation of the Sm in descending modulation of pain.