Bajrović F, Sketelj J
Institute of Pathophysiology, School of Medicine, University of Ljubljana, Slovenia.
Exp Neurol. 1998 Mar;150(1):115-21. doi: 10.1006/exnr.1997.6734.
Nociceptive innervation territories of individual peripheral and spinal nerves in the skin of the rat hind paw were investigated. In addition, the hypothesis that competitive interactions among the axons from adjacent dorsal root ganglia (DRG) play an important role in maintenance of dermatomal extent in adult animals was tested. The area of innervation territories of individual spinal and peripheral nerves was determined by nociceptive pinch test of the skin after extirpation of adjacent DRGs or transection of adjacent peripheral nerves, respectively. Positions of nociceptive dermatomes and innervation territories of peripheral nerves were similar to the territories innervated by the C-fibers described earlier by dye extravasation technique. In contrast, our results convincingly demonstrated substantial overlap of nociceptive (probably A delta) fibers from adjacent dermatomes in which the autonomous innervation areas were only about one-half of the maximal areas. Nociceptive territories of peripheral nerves overlapped, too. Accordingly, we could find no autonomous innervation area of the sural nerve. Two weeks after extirpation of adjacent DRGs, the area of each of the isolated dermatomes L3, L4, and L5 increased only by about 10%, and it did not change detectably during the next 6 months. The results of our study (a) support the view that innervation fields supplied by the nociceptive (probably A delta) fibers are greater and display more overlap than those supplied by the C-fibers of the same nerve and (b) suggest that axonal competition for innervation territory is not decisive for maintenance of dermatomal borders in the adult rat.
对大鼠后爪皮肤中各外周神经和脊髓神经的伤害性神经支配区域进行了研究。此外，还测试了相邻背根神经节（DRG）轴突间的竞争相互作用在成年动物皮节范围维持中起重要作用这一假说。分别通过切除相邻DRG后对皮肤进行伤害性捏压试验或切断相邻外周神经后对皮肤进行伤害性捏压试验，来确定各脊髓神经和外周神经的神经支配区域面积。伤害性皮节和外周神经的神经支配区域位置与先前用染料外渗技术描述的由C纤维支配的区域相似。相比之下，我们的结果令人信服地表明，相邻皮节的伤害性（可能是Aδ）纤维存在大量重叠，其中自主支配区域仅约为最大区域的一半。外周神经的伤害性区域也有重叠。因此，我们未发现腓肠神经的自主支配区域。切除相邻DRG两周后，分离出的L3、L4和L5每个皮节的面积仅增加约10%，且在接下来的6个月内无明显变化。我们的研究结果（a）支持这样一种观点，即伤害性（可能是Aδ）纤维提供的神经支配区域比同一神经的C纤维提供的神经支配区域更大且重叠更多，（b）表明轴突对神经支配区域的竞争对成年大鼠皮节边界的维持并非决定性因素。
