Schaible H G, Freudenberger U, Neugebauer V, Stiller R U
Physiologisches Institut, Universität Würzburg, Germany.
Neuroscience. 1994 Oct;62(4):1293-305. doi: 10.1016/0306-4522(94)90361-1.
This study addressed the intraspinal release of immunoreactive calcitonin gene-related peptide in vivo during mechanical stimulation of the normal joint and during the development of an acute experimental inflammation in the knee joint in the anaesthetized cat (spinalized) and rat (not spinalized). Release was assessed using microprobes coated with antibody to calcitonin gene-related peptide; inhibition of binding of [125I]calcitonin gene-related peptide to these probes following insertion into the spinal cord is equated with intraspinal release of the endogenous (unlabelled) peptide. Probes inserted prior to inflammation showed marked basal release of immunoreactive calcitonin gene-related peptide in the dorsal horn with a maximum in the superficial dorsal horn in the absence of intentional stimulation. The pattern of binding of [125I]calcitonin gene-related peptide was not or only minimally changed by innocuous mechanical stimuli (flexion of and innocuous pressure to the knee in the cat and innocuous pressure to the knee of the rat) but was significantly altered by electrical stimulation of the tibial nerve in the cat (sufficient to excite unmyelinated afferent fibres), indicating release of the peptide by the latter stimulus. During the first hours of the development of an experimental inflammation in the knee joint induced by intra-articular injections of kaolin and carrageenan, the pattern of binding of [125I]calcitonin gene-related peptide changed. In the cat, the level of immunoreactive calcitonin gene-related peptide showed a persistent increase in the gray matter and up to the surface of the cord and release was slightly increased by innocuous stimuli. In the rat, increased levels of immunoreactive calcitonin gene-related peptide were mainly seen in the superficial and deep dorsal horn during innocuous pressure (this stimulus did not evoke release of the peptide prior to inflammation) and noxious pressure applied to the injected knee, whereas increased basal levels were only observed at later stages. These data show that the development of an acute experimental inflammation in the joint is associated with an enhancement of the intraspinal release of immunoreactive calcitonin gene-related peptide. Since the changes in the release were noted at an early stage, within the first hours, they could contribute to the generation of inflammation-evoked changes of the responsiveness of spinal cord neurons and hence to the mechanisms inducing inflammatory pain.
本研究探讨了在正常关节机械刺激过程中以及在麻醉猫（脊髓横断）和大鼠（未脊髓横断）膝关节急性实验性炎症发展过程中，体内免疫反应性降钙素基因相关肽在脊髓内的释放情况。使用包被有降钙素基因相关肽抗体的微探针评估释放情况；将[125I]降钙素基因相关肽插入脊髓后与这些探针结合的抑制等同于内源性（未标记）肽在脊髓内的释放。在炎症发生前插入的探针显示，在背角中免疫反应性降钙素基因相关肽有明显的基础释放，在无故意刺激的情况下，浅表背角释放量最大。无害机械刺激（猫膝关节的屈曲和无害压力以及大鼠膝关节的无害压力）对[125I]降钙素基因相关肽的结合模式没有影响或仅有极小的改变，但猫的胫神经电刺激（足以激发无髓传入纤维）则显著改变了结合模式，表明后一种刺激可导致该肽的释放。在通过关节内注射高岭土和角叉菜胶诱导膝关节实验性炎症发展的最初几个小时内，[125I]降钙素基因相关肽的结合模式发生了变化。在猫中，免疫反应性降钙素基因相关肽的水平在灰质中持续升高直至脊髓表面，无害刺激可使释放量略有增加。在大鼠中，在无害压力（该刺激在炎症发生前不会引起该肽的释放）和对注射膝关节施加有害压力期间，免疫反应性降钙素基因相关肽水平的升高主要见于浅表和深部背角，而基础水平的升高仅在后期观察到。这些数据表明，关节急性实验性炎症的发展与免疫反应性降钙素基因相关肽在脊髓内释放的增强有关。由于在炎症发生后的最初几个小时内就注意到了释放的变化，它们可能有助于引发炎症引起的脊髓神经元反应性变化，从而参与诱导炎性疼痛的机制。
