Qiao Jian-Tian, Dafny Nachum
Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, P.O. Box 20708, Houston, TX 77225 U.S.A.
Pain. 1988 Jul;34(1):65-74. doi: 10.1016/0304-3959(88)90183-2.
A study on the nociceptive responses of single cells within the nucleus parafascicularis (PF) thalami of the rat was undertaken to clarify the reported observations of a pain suppression pathway to this nucleus from the dorsal raphe (DR) nucleus. Two types of nociceptive neuron were identified in the PF which were classified as 'nociceptive-on' and 'nociceptive-off' neurons, respectively. DR stimulation exhibits a simple monophasic 'dose-dependent' relationship between the degree of the inhibition elicited and the stimulation intensity used on the 'nociceptive-off' cells. In contrast, biphasic effects following DR stimulation on the 'nociceptive-on' cells was obtained, with low intensities eliciting suppression while high intensities excited the cells. These effects of low intensity DR stimulation upon the responses of the 'nociceptive-on' cells were diminished but not prevented by transection of the well-known bulbospinal inhibitory fibers descending in the dorsal half of the spinal cord, while the effects of DR stimulation upon the 'nociceptive-off' cells remain unchanged following spinal transection. Thus, our results show that DR stimulation modulates the nociceptive responsiveness of the PF by way of supraspinal pathways in addition to the previously described descending paths.
为了阐明从背侧中缝核（DR）到束旁核（PF）丘脑存在痛觉抑制通路这一已报道的观察结果，我们对大鼠丘脑束旁核内的单细胞伤害性反应进行了研究。在PF中鉴定出两种类型的伤害性神经元，分别归类为“伤害性开启”和“伤害性关闭”神经元。DR刺激在“伤害性关闭”细胞上所引发的抑制程度与所用刺激强度之间呈现出简单的单相“剂量依赖性”关系。相反，DR刺激对“伤害性开启”细胞产生双相效应，低强度刺激引起抑制，而高强度刺激则使细胞兴奋。低强度DR刺激对“伤害性开启”细胞反应的这些效应，在切断脊髓背侧下行的著名延髓脊髓抑制纤维后减弱但未被阻止，而脊髓横断后DR刺激对“伤害性关闭”细胞的效应保持不变。因此，我们的结果表明，DR刺激除了通过先前描述的下行通路外，还通过脊髓上通路调节PF的伤害性反应性。
