α_2肾上腺素受体在神经病理性疼痛大鼠脊髓背角中的表达

EXPRESSION OF ALPHA 2 ADRENERGIC RECEPTOR SUBTYPES IN DORSAL HORN NEURONS OF RATS UNDER NEUROPATHIC PAIN CONDITIONS

目的:研究α2肾上腺素受体(α2-AR)不同亚型在神经病理性疼痛大鼠中的表达变化规律及其在神经病理性疼痛形成中作用。方法:雄性6周龄SD大鼠分为对照组、假手术组和保留性脊神经损伤模型组(spared nerve injury,SNI组)。采用蛋白质免疫印迹法(Western blot法)和RT-PCR法测定α2A-AR、α2B-AR和α2C-AR在腰膨大段脊髓背角中的表达。结果:(1)在蛋白水平三个亚型在正常大鼠均有表达,主要是以α2A-AR为主;(2)与正常组和假手术组比较,SNI神经病理性疼痛组α2A-AR的蛋白表达明显下调(P<0.01,n=6),而α2B-AR和α2C-AR蛋白表达则没有明显的变化(P>0.05,n=6)。(3)在m RNA水平,三个亚型在三组表达没有明显的变化(P>0.05,n=5)。结论:在神经病理性疼痛条件下,脊髓背角α2A-AR受体亚型明显下调,α2B-AR和α2C-AR没有明显变化,表明这种下调仅发生在翻译水平而非转录水平。α2A-AR下调可能在外周神经损伤所引起的神经病理性疼痛中发挥作用。

Objective：To investigate the dynamic expression and distribution of Alpha 2 adrenergic receptor subtypes in the rat＇s spinal dorsal horn neurons （SDH） under neuropathic pain conditions.Methods：Six weeks old male SD rats were randomly divided into normal control group （naive,n =6）,sham-operated group （n =6） and SNI （spared nerve injury） group （n =6）.The expression of protein and mRNA level of three alpha 2 adrenergic receptor subtypes （α 2A-AR,α 2B-AR,and α 2C-AR） which performed on L4-6 lumbar enlargement SDH neurons were measured by Westem blot and RT-PCR methods.Results：（1） All three alpha 2 adrenergic receptor subtypes expression was found by Western Blot at protein level in SDH neurons in all groups.The Alpha 2A adrenergic subtype distribution was dominated in normal rats.（2） The expression of Alpha 2A was decreased significantly under neuropathic conditions at protein level but no changes were found in sham-operated and normal control groups.There were no changes of Alpha 2B and 2C subtypes expression in all groups at protein level.（3）The RT-PCR results showed that Alpha adrenergic subtypes mRNA expression did not change under neuropathic conditions.Conclusion：The down-regulation of Alpha 2A in the spinal dorsal hom occurs after peripheral nerve ligation.The down-regulation was performed at protein expressing level but not at the transcription level.The dorsal hom adrenergic receptor down-regulation may play an important role in the development of neuropathic pain.