Fecho Karamarie, Nackley Andrea G, Wu Ying, Maixner William
Department of Anesthesiology, Division of Pain Medicine, School of Medicine, The University of North Carolina at Chapel Hill, CB #7010, 451 MacNider Hall, Chapel Hill, North Carolina 27599-7010, USA.
Physiol Behav. 2005 Jun 2;85(2):177-86. doi: 10.1016/j.physbeh.2005.03.018.
Individual differences in pain sensitivity are believed to reflect the interplay of many factors, including genetics. Inbred rat strains can be used to study the impact of genetic factors on pain sensitivity. Inbred Lewis (LEW) and Fischer 344 (FIS) rat strains display profound and contrasting alterations in neuroendocrine, immunological and behavioral responses to stressors. Because of the established interactions between stressors, the neuroendocrine system, the immune system and pain processing pathways, we hypothesized that LEW and FIS rats would differ in their pain sensitivity. Pain sensitivity was assessed using several behavioral pain assays in untreated and carrageenan-inflamed LEW and FIS rats, and in the outbred Sprague-Dawley (SD) rat. The results showed that at baseline, FIS rats were the most sensitive to mechanical stimulation (the von Frey monofilament test) and the least sensitive to noxious heat pain (the Hargreaves radiant heat test). After intraplantar administration of carrageenan, LEW rats showed the least, and FIS rats showed the greatest, thermal hyperalgesia and mechanical allodynia/hyperalgesia. Hindlimb muscle grip force and tail-flick latencies did not differ across the three strains, either before or after carrageenan. These results demonstrate differences in basal and carrageenan-induced pain sensitivity in LEW, FIS and SD rats, which extend earlier findings that genetic factors modulate both basal and inflammatory pain. The results further demonstrate that basal pain sensitivity can be predictive of inflammatory pain sensitivity, with the direction of the effect dependent upon the pain measure.
疼痛敏感性的个体差异被认为反映了包括遗传学在内的多种因素的相互作用。近交系大鼠品系可用于研究遗传因素对疼痛敏感性的影响。近交系刘易斯（LEW）大鼠和费希尔344（FIS）大鼠品系在对应激源的神经内分泌、免疫和行为反应方面表现出深刻且相反的变化。由于应激源、神经内分泌系统、免疫系统和疼痛处理途径之间已确定的相互作用，我们推测LEW和FIS大鼠在疼痛敏感性上会存在差异。我们使用多种行为性疼痛测定方法，对未处理的和角叉菜胶致炎的LEW和FIS大鼠以及远交系斯普拉格-道利（SD）大鼠的疼痛敏感性进行了评估。结果显示，在基线时，FIS大鼠对机械刺激（von Frey单丝试验）最为敏感，而对伤害性热痛（哈格里夫斯辐射热试验）最不敏感。在足底注射角叉菜胶后，LEW大鼠的热痛觉过敏和机械性异常性疼痛/痛觉过敏程度最低，而FIS大鼠的最高。在注射角叉菜胶前后，三个品系的后肢肌肉握力和甩尾潜伏期均无差异。这些结果表明，LEW、FIS和SD大鼠在基础疼痛敏感性和角叉菜胶诱导的疼痛敏感性方面存在差异，这扩展了早期关于遗传因素调节基础疼痛和炎症性疼痛的研究结果。结果还进一步表明，基础疼痛敏感性可以预测炎症性疼痛敏感性，其影响方向取决于疼痛测量指标。
