Reynolds M L, Fitzgerald M
Department of Anatomy and Developmental Biology, University College London, United Kingdom.
J Comp Neurol. 1995 Aug 7;358(4):487-98. doi: 10.1002/cne.903580403.
Skin innervation during wound healing was investigated using immunocytochemical staining with the panneuronal marker antiprotein gene product (PGP) 9.5, which labels the entire innervation of the skin throughout development and in the adult. Full-thickness skin wounds in the hairy skin of the foot in neonatal rats result in pronounced hyperinnervation of the tissue that persists long after the wound has healed (at least 12 weeks). Quantification of this hyperinnervation by image analysis indicates that skin innervation density in the wounded area can increase up to 300%. The effect is greatest when wounds are performed at postnatal day (P) 0 or 7, declining when performed at P14 and P21 to resemble the weaker and transient effect in the adult. Staining with selective markers for different neuronal populations innervating skin (monoclonal anti-RT97 staining the myelinated axons of large light sensory ganglion cells; anticalcitonin gene-related peptide staining unmyelinated C axons, thinly myelinated A delta axons, and a subpopulation of large A fibres) reveal that both A- and C-fibre sensory axons contribute to this response. Destruction of the majority of the C-fibre population with neonatal capsaicin pretreatment, which leaves large A fibres intact, significantly reduces the hyperinnervation response at 14 days, confirming a major contribution from both A and C fibres. Sympathetic axons, stained with anti-tyrosine hydroxylase, do not sprout into the wounded area. Furthermore, pretreatment of neonates with 6-hydroxydopamine, which destroys the sympathetic innervation, does not significantly reduce the overall sprouting response, as identified by anti-PGP9.5 staining. Behavioural sensory testing revealed a 50% drop in the mechanical threshold in the wounded area after 3 weeks. These remarkably long-term and specific effects on sensory terminal axons following neonatal skin wounding indicate the plasticity of cutaneous innervation density following alterations in the target tissue at a critical stage of development.
利用全神经元标记物抗蛋白基因产物（PGP）9.5进行免疫细胞化学染色，对伤口愈合过程中的皮肤神经支配进行了研究，该标记物可标记皮肤在整个发育过程及成体中的全部神经支配。新生大鼠足部有毛皮肤的全层皮肤伤口会导致组织明显的神经纤维过度生长，这种现象在伤口愈合后很长时间（至少12周）仍然存在。通过图像分析对这种神经纤维过度生长进行量化，结果表明，伤口区域的皮肤神经支配密度可增加高达300%。当在出生后第（P）0天或第7天进行伤口处理时，这种效应最为明显，而在P14和P21进行伤口处理时，效应减弱，类似于成体中较弱且短暂的效应。用针对支配皮肤的不同神经元群体的选择性标记物进行染色（单克隆抗RT97染色大型浅感觉神经节细胞的有髓轴突；抗降钙素基因相关肽染色无髓C轴突、薄髓Aδ轴突以及一部分大型A纤维）显示，A纤维和C纤维感觉轴突均参与了这一反应。用新生辣椒素预处理破坏大部分C纤维群体（大型A纤维保持完整），可显著降低14天时的神经纤维过度生长反应，证实A纤维和C纤维均起主要作用。用抗酪氨酸羟化酶染色的交感神经轴突不会向伤口区域生长。此外，用6-羟基多巴胺预处理新生大鼠以破坏交感神经支配，通过抗PGP9.5染色鉴定，并未显著降低整体的神经纤维生长反应。行为感觉测试显示，3周后伤口区域的机械阈值下降了50%。新生皮肤受伤后对感觉终末轴突产生的这些显著的长期且特异性效应表明，在发育的关键阶段，靶组织发生改变后，皮肤神经支配密度具有可塑性。
