After peripheral nerve injury, regeneration or collateral sprouting of noradrenergic nerve fibres in the papillary dermis of the injured limb may contribute to sympathetically-maintained pain. The aim of this study was to determine whether noradrenergic nerve fibre regeneration after partial sciatic nerve ligation (PSL) in Wistar rats was accompanied by parallel shifts in expression of the noradrenaline transporter (NAT). Four or 28 days after PSL surgery, immunohistochemistry was used to examine NAT expression in plantar hind paw skin in relation to pan-neuronal markers (class III beta-tubulin and protein gene product 9.5), peptidergic afferents containing calcitonin gene-related peptide (CGRP), nonpeptidergic afferents labelled by isolectin B4 (IB4), and tyrosine hydroxylase (TH), a marker for cutaneous noradrenergic nerve fibres. Most dermal nerve fibre populations decreased shortly after PSL. However, four weeks after PSL, an increase in staining intensity of CGRP and novel expression of TH were observed in the papillary dermis on the injured side. In contrast, neural expression of NAT was reduced in this region. Loss of NAT might have implications for sympathetically-maintained pain, as failure to rapidly clear noradrenaline could exacerbate aberrant sympathetic-sensory signalling between closely apposed noradrenergic and peptidergic nerve fibres.

中文翻译：

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坐骨神经部分损伤后真皮乳头层去甲肾上腺素转运蛋白的神经表达降低

外周神经损伤后，受伤肢体的乳头状真皮中去甲肾上腺素能神经纤维的再生或侧枝萌发可能导致交感神经维持的疼痛。本研究的目的是确定 Wistar 大鼠部分坐骨神经结扎 (PSL) 后去甲肾上腺素能神经纤维再生是否伴有去甲肾上腺素转运蛋白 (NAT) 表达的平行变化。PSL 手术后 4 天或 28 天，使用免疫组织化学检查足底后爪皮肤中 NAT 表达与泛神经元标记物（III 类β-微管蛋白和蛋白质基因产物 9.5）、含有降钙素基因相关肽 (CGRP) 的肽能传入)、由异凝集素 B4 (IB4) 和酪氨酸羟化酶 (TH) 标记的非肽能传入神经，这是一种皮肤去甲肾上腺素能神经纤维的标记物。大多数真皮神经纤维数量在 PSL 后不久就减少了。然而，在 PSL 后 4 周，在受伤侧的乳头状真皮中观察到 CGRP 染色强度的增加和 TH 的新表达。相比之下，该区域中 NAT 的神经表达减少。NAT 的丧失可能对交感神经维持的疼痛产生影响，因为不能快速清除去甲肾上腺素可能会加剧紧密并列的去甲肾上腺素能和肽能神经纤维之间的异常交感神经感觉信号。