慢性痛的挑战

THE CHALLENGE OF CHRONIC PAIN

虽然痛被用来描述所有真正或潜在的组织损伤或用损伤描述的一种不愉快的感觉和情绪,但实际上痛有两种:第一种是伤害性痛,这种痛是生理性的,与伤害性刺激有关;第二种是临床痛,它有急性与慢性之别。急性痛源于软组织损伤和炎症,具有生物学意义;慢性痛是由神经病理改变所引起的持续性感觉异常,难于治疗。很多分子可能在伤害性痛机制中起重要作用,如经典神经递质、神经肽、质子和三磷酸腺苷等。然而新近的研究结果表明,在周围神经损伤后初级感觉神经细胞中的一氧化氮合酶、神经肽及其受体的表达发生了明显变化,这种初级感觉神经细胞的新的细胞表现型可能与周围神经损伤后常发生慢性痛的起因有关。这些结果有力地提示,慢性痛具有有别于伤害性痛和急性痛的分子和细胞机制。慢性痛研究的快速发展不仅使我们对痛机制有新认识,而且将为治疗慢性痛提供理论基础。

t Although the term pain is used to define all sensations that hurt or are unpleasant, actually two distinct kinds of pain exist. The first kind of pain, which is nociceptive, is physiological and links with noxious stimuli. The second kind of pain is clinical, and can be either acute or chronic. Acute pain results from soft tissue injury or inflammation, and has biologically useful functions. Chronic pain, which is a sustained sensory abnormality caused by neuropathological change, is difficult to be treated. For a very long time neuroscientists have tried to find the mechanism of pain, especially nociceptive pain. Many molecules, such as classic neurotransmitters, neuropeptides, nitric oxide, protons, adenosine 5'-triphosphate, have been suspected to play important roles in nociceptive pain. However, recent studies have shown that the expression of neuropeptides, receptors , nitric oxide synthase is markedly changed in primary sensory neurons following peripheral axotomy. The new phenotype of primary sensory neurons may be related to the causes of the chronic pain which often occurs after peripheral nerve injury. These results strongly suggest that chronic pains may have molecular and cellular mechanisms which are different from nociceptive pain and acute pain. Such rapid development in the study of chronic pain will not only lead to new insight of pain mechanism, but also offer the potential for developing novel therapeutic strategies for treating chronic pain.