Dostrovsky J O, Guilbaud G
Department of Physiology, University of Toronto, Ont., Canada.
Brain Res. 1988 Sep 20;460(2):269-80. doi: 10.1016/0006-8993(88)90372-1.
Anatomical studies have revealed the existence of an ascending pathway originating in the spinal cord and medullary dorsal horn, relaying in nucleus submedius (Sm) in medial thalamus and terminating in ventrolateral orbital cortex. It has been suggested that this pathway may be involved in the transmission of nociceptive information. In the present study extracellular recordings were obtained from neurons in Sm of anesthetized arthritic and normal rats. Mechanical and thermal stimuli were delivered to various regions of the body to determine the types of somatic stimuli which could activate Sm neurons. Over 40% of the 146 neurons studied responded to somatic stimuli. In the normal rats only high intensity mechanical and thermal stimuli were effective in inducing responses. In the arthritic rats lower intensity mechanical stimuli, joint movements and high intensity thermal stimuli were effective. Such stimuli produce nociceptive reactions in the freely moving arthritic rat. Almost all the responses were excitatory and generally lasted the entire duration of the 15-s stimuli employed. In some cases after-discharges were present. The receptive fields of the neurons were in almost all cases large and bilateral. These findings support the hypothesis that Sm may be involved in mediating the affective-motivational aspects of pain.
解剖学研究显示，存在一条起源于脊髓和延髓背角的上行通路，该通路在内侧丘脑的中介核（Sm）中继，并终止于腹外侧眶皮质。有人提出，这条通路可能参与伤害性信息的传递。在本研究中，从麻醉的关节炎大鼠和正常大鼠的Sm核中的神经元获得了细胞外记录。对身体的各个区域施加机械和热刺激，以确定能够激活Sm神经元的躯体刺激类型。在研究的146个神经元中，超过40%对躯体刺激有反应。在正常大鼠中，只有高强度的机械和热刺激能有效诱导反应。在关节炎大鼠中，较低强度的机械刺激、关节运动和高强度的热刺激是有效的。这些刺激在自由活动的关节炎大鼠中产生伤害性反应。几乎所有的反应都是兴奋性的，并且通常持续所用15秒刺激的整个持续时间。在某些情况下会出现后放电。几乎在所有情况下，神经元的感受野都很大且双侧分布。这些发现支持了Sm可能参与介导疼痛的情感-动机方面的假说。
