Departments of Neurology and.
Neurobiology and Anatomy.
Pain. 2020 Aug;161(8):1884-1893. doi: 10.1097/j.pain.0000000000001865. Epub 2020 Mar 9.
The endogenous opioidergic system is critically involved in the cognitive modulation of pain. Slow-breathing-based techniques are widely used nonpharmacological approaches to reduce pain. Yet, the active mechanisms of actions supporting these practices are poorly characterized. Growing evidence suggest that mindfulness-meditation, a slow-breathing technique practiced by nonreactively attending to breathing sensations, engages multiple unique neural mechanisms that bypass opioidergically mediated descending pathways to reduce pain. However, it is unknown whether endogenous opioids contribute to pain reductions produced by slow breathing. The present double-blind, placebo-controlled crossover study examined behavioral pain responses during mindfulness-meditation (n = 19), sham-mindfulness meditation (n = 20), and slow-paced breathing (n = 20) in response to noxious heat (49°C) and intravenous administration (0.15 mg/kg bolus + 0.1 mg/kg/hour maintenance infusion) of the opioid antagonist, naloxone, and placebo saline. Mindfulness significantly reduced pain unpleasantness ratings across both infusion sessions when compared to rest, but not pain intensity. Slow-paced breathing significantly reduced pain intensity and unpleasantness ratings during naloxone but not saline infusion. Pain reductions produced by mindfulness-meditation and slow-paced breathing were insensitive to naloxone when compared to saline administration. By contrast, sham-mindfulness meditation produced pain unpleasantness reductions during saline infusion but this effect was reversed by opioidergic antagonism. Sham-mindfulness did not lower pain intensity ratings. Self-reported "focusing on the breath" was identified as the operational feature particularly unique to the mindfulness-meditation and slow paced-breathing, but not sham-mindfulness meditation. Across all individuals, attending to the breath was associated with naloxone insensitive pain-relief. These findings provide evidence that slow breathing combined with attention to breath reduces pain independent of endogenous opioids.
内源性阿片样物质系统在疼痛的认知调节中起着至关重要的作用。基于缓慢呼吸的技术是广泛使用的非药物方法，可减轻疼痛。然而，支持这些实践的积极作用机制尚未得到很好的描述。越来越多的证据表明，正念冥想，一种通过非反应性地关注呼吸感觉来进行的缓慢呼吸技术，涉及到多种独特的神经机制，这些机制绕过了阿片介导的下行途径，从而减轻了疼痛。然而，目前还不清楚内源性阿片类物质是否有助于缓慢呼吸引起的疼痛减轻。本双盲、安慰剂对照交叉研究在 19 名参与者中观察了正念冥想（n = 19）、假正念冥想（n = 20）和缓慢呼吸（n = 20）期间对疼痛的行为反应，这些参与者在静脉注射阿片拮抗剂纳洛酮（0.15mg/kg 推注+0.1mg/kg/h 维持输注）和安慰剂生理盐水时，分别接受了有害热（49°C）和有害热（49°C）刺激。与休息相比，正念冥想在两次输注过程中均显著降低了疼痛不适评分，但不降低疼痛强度。在纳洛酮输注期间，缓慢呼吸显著降低了疼痛强度和不适评分，但在生理盐水输注期间则不然。与生理盐水相比，纳洛酮对正念冥想和缓慢呼吸引起的疼痛缓解作用不敏感。相比之下，假正念冥想在生理盐水输注时可降低疼痛不适评分，但这种作用在阿片类药物拮抗后被逆转。假正念冥想没有降低疼痛强度评分。自我报告的“专注于呼吸”被确定为正念冥想和缓慢呼吸特别独特的操作特征，但假正念冥想则没有。在所有个体中，关注呼吸与纳洛酮不敏感的疼痛缓解相关。这些发现为缓慢呼吸结合注意力呼吸可减轻疼痛且不依赖内源性阿片类物质提供了证据。
