Venezia Alessandra, Jones Harriet-Fawsitt, Hohenschurz-Schmidt David, Mancini Matteo, Howard Matthew, Makovac Elena
Department of Neuroimaging, Institute of Psychology, Psychiatry & Neuroscience, King's College London, London, UK.
Department of Surgery & Cancer, Imperial College London, London, UK.
J Physiol. 2024 Dec;602(24):6941-6957. doi: 10.1113/JP286375. Epub 2024 Oct 9.
The autonomic nervous system (ANS) and pain exhibit a reciprocal relationship, where acute pain triggers ANS responses, whereas resting ANS activity can influence pain perception. Nociceptive signalling can also be altered by 'top-down' processes occurring in the brain, brainstem and spinal cord, known as 'descending modulation'. By employing the conditioned pain modulation (CPM) paradigm, we previously revealed a connection between reduced low-frequency heart rate variability and CPM. Individuals with chronic pain often experience both ANS dysregulation and impaired CPM. Baroreceptors, which contribute to blood pressure and heart rate variability regulation, may play a significant role in this relationship, although their involvement in pain perception and their functioning in chronic pain have not been sufficiently explored. In the present study, we combined artificial 'baroreceptor stimulation' in both pressure pain and CPM paradigms, seeking to explore the role of baroreceptors in pain perception and descending modulation. In total, 22 individuals with chronic low back pain (CLBP) and 29 individuals with no-pain (NP) took part in the present study. We identified a differential modulation of baroreceptor stimulation on pressure pain between the groups of NP and CLBP participants. Specifically, NP participants perceived less pain in response to baroreflex activation, whereas CLBP participants exhibited increased pain sensitivity. CPM scores were associated with baseline measures of baroreflex sensitivity in both CLBP and NP participants. Our data support the importance of the baroreflex in chronic pain and a possible mechanism of dysregulation involving the interaction between the ANS and descending pain modulation. KEY POINTS: Baroreflex stimulation has different effects on pressure pain in participants with chronic pain compared to matched individuals with no-pain. Baroreceptor activation decreases pain in participants with no-pain but increases pain perception in participants with chronic pain. Baroreflex sensitivity is associated with conditioned pain modulation in both groups of chronic pain and no-pain participants. The reactivity of the baroreflex during autonomic stress demonstrated a positive correlation with Pain Trait scores in participants with chronic back pain.
自主神经系统（ANS）与疼痛之间存在相互关系，急性疼痛会引发自主神经系统反应，而自主神经系统的静息活动则会影响疼痛感知。伤害性信号也会受到大脑、脑干和脊髓中发生的“自上而下”过程（即“下行调制”）的改变。通过采用条件性疼痛调制（CPM）范式，我们之前揭示了低频心率变异性降低与CPM之间的联系。慢性疼痛患者通常会经历自主神经系统失调和CPM受损。压力感受器有助于调节血压和心率变异性，可能在这种关系中起重要作用，尽管它们在疼痛感知中的参与以及在慢性疼痛中的功能尚未得到充分研究。在本研究中，我们在压力疼痛和CPM范式中都采用了人工“压力感受器刺激”，旨在探索压力感受器在疼痛感知和下行调制中的作用。共有22名慢性下腰痛（CLBP）患者和29名无疼痛（NP）个体参与了本研究。我们发现压力感受器刺激对NP组和CLBP组参与者的压力疼痛有不同的调制作用。具体而言，NP组参与者在压力反射激活时感觉到的疼痛较轻，而CLBP组参与者则表现出疼痛敏感性增加。CLBP组和NP组参与者的CPM评分均与压力反射敏感性的基线测量值相关。我们的数据支持压力反射在慢性疼痛中的重要性以及涉及自主神经系统与下行疼痛调制相互作用的失调可能机制。要点：与匹配的无疼痛个体相比，压力反射刺激对慢性疼痛参与者的压力疼痛有不同影响。压力感受器激活可减轻无疼痛参与者的疼痛，但会增加慢性疼痛参与者的疼痛感知。压力反射敏感性在慢性疼痛组和无疼痛组参与者中均与条件性疼痛调制相关。自主应激期间压力反射的反应性与慢性背痛参与者的疼痛特质评分呈正相关。
