Ramien Michele, Ruocco Isabella, Cuello A Claudio, St-Louis Manon, Ribeiro-Da-Silva Alfredo
Department of Pharmacology & Therapeutics, McGill University, Montréal, Québec H3G 1Y6, Canada.
J Comp Neurol. 2004 Jan 26;469(1):83-95. doi: 10.1002/cne.10998.
The sympathetic division of the autonomic nervous system is known to play a role in the genesis of neuropathic pain. In the skin of the rat lower lip (hairy skin), sympathetic and parasympathetic fibers normally innervate the same blood vessels in the lower dermis but do not occur in the upper dermis. However, we have shown that sympathetic fiber migration into the upper dermis occurs following mental nerve lesions (Ruocco et al. [2000] J. Comp. Neurol. 422:287-296). As sensory denervation has a dramatic effect on sympathetic fiber innervation patterns in the rat lower lip skin, we decided to investigate the possible changes in the other autonomic fiber type in the skin-the parasympathetic fiber. Sensory denervation of the rat lower lip was achieved by bilateral transection of the mental nerve, and animals were allowed to recover for 1-8 weeks. Lower lip tissue was processed for double-labeling light microscopic immunocytochemistry (ICC), using antibodies against substance P (SP), which labels a subpopulation of peptidergic sensory fibers, and against the vesicular acetycholine transporter (VAChT), as a marker for parasympathetic fibers. In sham-operated rats, SP-immunoreactive (IR) sensory fibers were found in the epidermis and upper and lower dermal regions, whereas VAChT-IR fibers were confined to the lower dermis. Mental nerve lesions induced the gradual disappearance of SP-IR fibers from all skin layers accompanied by the progressive migration of VAChT-IR fibers into the upper dermis. Cholinergic fiber migration was evident by the second week post surgery, and the ectopic innervation of the upper dermis by these fibers persisted even at the last time point studied (8 weeks) when SP-IR fibers have completely regrown. VAChT-IR fibers were observed in the upper dermis, well above the opening of the sebaceous glands into the hair follicles. These results show that considerable changes occur in the innervation patterns of parasympathetic fibers following mental nerve lesions.
已知自主神经系统的交感神经部分在神经性疼痛的发生中起作用。在大鼠下唇皮肤（有毛皮肤）中，交感神经和副交感神经纤维通常支配真皮下部的相同血管，但在上部真皮中不存在。然而，我们已经表明，在颏神经损伤后，交感神经纤维会迁移到上部真皮中（Ruocco等人，[2000]《比较神经学杂志》422:287 - 296）。由于感觉去神经支配对大鼠下唇皮肤中的交感神经纤维支配模式有显著影响，我们决定研究皮肤中另一种自主神经纤维类型——副交感神经纤维可能发生的变化。通过双侧切断颏神经实现大鼠下唇的感觉去神经支配，让动物恢复1 - 8周。使用针对P物质（SP）的抗体（标记肽能感觉纤维的一个亚群）和针对囊泡乙酰胆碱转运体（VAChT）的抗体（作为副交感神经纤维的标记物），对下唇组织进行双重标记光镜免疫细胞化学（ICC）处理。在假手术大鼠中，SP免疫反应性（IR）感觉纤维见于表皮以及真皮上部和下部区域，而VAChT - IR纤维局限于真皮下部。颏神经损伤导致所有皮肤层中SP - IR纤维逐渐消失，同时VAChT - IR纤维逐渐迁移到上部真皮中。胆碱能纤维迁移在术后第二周就很明显，并且即使在研究的最后时间点（8周），当SP - IR纤维已经完全重新生长时，这些纤维对上真皮的异位支配仍然存在。在皮脂腺开口进入毛囊上方的上部真皮中观察到了VAChT - IR纤维。这些结果表明，颏神经损伤后副交感神经纤维的支配模式发生了相当大的变化。
