Lambertz D, Hoheisel U, Mense S
Institute of Anatomy and Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, D-69120 Heidelberg, Germany.
Eur J Pain. 2008 Aug;12(6):686-95. doi: 10.1016/j.ejpain.2007.10.015. Epub 2007 Dec 19.
A recent study of our group has shown that in the segments L4 and L5 of the rat, the synaptic field potentials (SFPs) evoked by tetrodotoxin-resistant (TTX-r, presumably nociceptive) muscle afferents differ in size and peak location from those of cutaneous afferents from the same body region [Lambertz D, Hoheisel U, Mense S. Distribution of synaptic field potentials induced by TTX-resistant skin and muscle afferents in rat segment L4 and L5. Neurosci Lett 2006;409:14-8]. Here, we investigated the influence of a muscle inflammation on the distribution of SFPs of TTX-r afferent fibres from muscle and skin in the thoracic and lumbar spinal cord. During a TTX block of the dorsal roots L3-L6, a skin nerve (sural, SU) or a muscle nerve (gastrocnemius-soleus, GS) were electrically stimulated at an intensity supramaximal for unmyelinated afferents and the SFPs recorded with tungsten microelectrodes. In control (non-inflamed) rats, the largest SFPs evoked by TTX-r GS afferents were recorded in laminae IV-VI with a maximum in segment L4, whereas the largest SU-induced SFPs were more superficially located with a maximum in L3. In chronic myositis animals, SFPs induced by GS TTX-r fibres exhibited significant decreases in lamina IV-VI of Th 12 and L5 as well as in lamina VII of L5. In contrast, SFPs evoked by SU TTX-r afferents showed significant increases in lamina IV-VI in L1 and in lamina VII in L4. The results demonstrate that a chronic myositis has a strong influence also on the synaptic effects of nociceptive afferents from the skin, which may explain the subjective cutaneous sensations during a pathological alteration of muscle.
我们团队最近的一项研究表明，在大鼠的L4和L5节段，由河豚毒素抗性（TTX-r，可能为伤害性）肌肉传入纤维诱发的突触场电位（SFP）在大小和峰值位置上与来自同一身体区域的皮肤传入纤维不同[Lambertz D，Hoheisel U，Mense S.大鼠L4和L5节段中TTX抗性皮肤和肌肉传入纤维诱发的突触场电位分布。神经科学快报2006；409：14 - 8]。在此，我们研究了肌肉炎症对胸段和腰段脊髓中来自肌肉和皮肤的TTX-r传入纤维SFP分布的影响。在L3 - L6背根的TTX阻断期间，以对无髓传入纤维为超最大强度电刺激一条皮肤神经（腓肠神经，SU）或一条肌肉神经（腓肠肌 - 比目鱼肌，GS），并用钨微电极记录SFP。在对照（未发炎）大鼠中，由TTX-r GS传入纤维诱发的最大SFP记录于IV - VI层，在L4节段达到最大值，而最大的SU诱发SFP位置更表浅，在L3节段达到最大值。在慢性肌炎动物中，GS TTX-r纤维诱发的SFP在Th 12和L5的IV - VI层以及L5的VII层显著降低。相反，SU TTX-r传入纤维诱发的SFP在L1的IV - VI层和L4的VII层显著增加。结果表明，慢性肌炎对来自皮肤的伤害性传入纤维的突触效应也有强烈影响，这可能解释了肌肉病理改变期间的主观皮肤感觉。
