Grubb B D, Stiller R U, Schaible H G
Physiologisches Institut, Universität Würzburg, Federal Republic of Germany.
Exp Brain Res. 1993;92(3):441-52. doi: 10.1007/BF00229032.
The aim of this study was to determine the discharge and receptive field properties of spinal cord neurons with ankle input in spinal segments L4-6 in the rat, both under control conditions and during the course of an adjuvant-induced unilateral inflammation in the ankle. The extent of receptive fields in the skin and deep tissue was assessed using brush, pinch and compression stimuli. Neurons were categorized as nociceptive-specific or wide-dynamic-range neurons on the basis of their response thresholds and responses to suprathreshold stimuli. At all stages of inflammation (2, 6, 13 and 20 days post inoculation) the population of neurons with ankle input showed differences from the population of neurons with ankle input in control rats. There was a reduction in the number of neurons that appeared as nociceptive specific and a concomitant increase in the number of neurons showing a wide-dynamic-range response profile. The receptive fields of the neurons with ankle input were markedly larger in rats with inflammation in the ankle region and mainly spread proximally on the ipsilateral hindlimb and also to the abdomen and tail in some cases. There was also an increase in the number of neurons with contralateral excitatory inputs. The mechanical thresholds at the ankle joint and proximal parts of the ipsilateral hindlimb were less in arthritic rats than in controls. The proportion of spontaneously active neurons was also increased in rats during the initial and later stages of inflammation, although there was no significant increase in the mean spontaneous discharge frequency. These data show that there are long-term changes in the receptive field and response properties of neurons in intact rats with chronic unilateral adjuvant-induced inflammation similar to those described previously in spinal cats with acute inflammation (Neugebauer and Schaible 1990). It is presumed that similar afferent and spinal mechanisms are at work under acute and chronic inflammatory conditions which produce hyperexcitability in spinal neurons with joint input.
本研究的目的是确定大鼠L4 - 6脊髓节段中接受踝关节传入的脊髓神经元在对照条件下以及在佐剂诱导的踝关节单侧炎症过程中的放电和感受野特性。使用刷擦、捏压和压迫刺激来评估皮肤和深部组织中感受野的范围。根据神经元的反应阈值和对阈上刺激的反应，将神经元分类为伤害性特异性神经元或广动力范围神经元。在炎症的所有阶段（接种后2、6、13和20天），接受踝关节传入的神经元群体与对照大鼠中接受踝关节传入的神经元群体存在差异。表现为伤害性特异性的神经元数量减少，同时表现出广动力范围反应模式的神经元数量相应增加。踝关节有炎症的大鼠中，接受踝关节传入的神经元的感受野明显更大，主要向同侧后肢近端扩展，在某些情况下还扩展到腹部和尾部。具有对侧兴奋性输入的神经元数量也增加。与对照组相比，关节炎大鼠踝关节和同侧后肢近端的机械阈值更低。在炎症的初始和后期阶段，大鼠中自发活动神经元的比例也增加，尽管平均自发放电频率没有显著增加。这些数据表明，在慢性单侧佐剂诱导炎症的完整大鼠中，神经元的感受野和反应特性存在长期变化，类似于先前在急性炎症的脊髓猫中所描述的变化（Neugebauer和Schaible，1990）。据推测，在急性和慢性炎症条件下，类似的传入和脊髓机制在起作用，导致具有关节传入的脊髓神经元兴奋性过高。
