Center for Biomedical Research on Pain (CBRP), College of Medicine, Xi'an Jiaotong University, Xi'an 710061, China.
Brain Res Bull. 2012 Apr 10;87(6):564-70. doi: 10.1016/j.brainresbull.2011.11.003. Epub 2011 Nov 12.
The aim of current study was to explore role of gender in pain and cutaneous vasomotor responses during the condition of intramuscular (i.m.) hypertonic (HT, 5.8%) saline induced muscle pain. In 20 healthy human subjects (10 females), 2-4.8ml of either HT or isotonic (IT, 0.9%) saline was infused into the left tibialis anterior muscle to elicit muscle pain, during which the intensity and distribution of pain together with skin vasomotor responses were investigated. Cutaneous blood flow was assessed using laser-Doppler flowmetry in 4 different skin areas: ipsilateral infusion area (5cm×5cm), ipsilateral referred pain area (5cm×10cm), contralateral area to the infusion site (5cm×5cm), and contralateral area to the referred pain site (5cm×10cm). Among the different i.m. infusions, 4.8ml HT saline evoked the highest pain intensity, the longest pain duration, and the largest pain distribution area in different subjects (P<0.001). Gender-related differences in pain and skin vasomotor responses were observed following the i.m. HT, but not IT, saline infusion while women exhibited stronger pain intensity and duration (P<0.001), and more expressed vasomotor responses (P<0.05) at the infusion area and contralateral mirror site. Intramuscularly pre-treating the infusion area with 1ml of 2% lidocaine markedly reduced the muscle pain and blocked the increased skin blood flow in both men and women (P<0.05). However, post-treatment with lidocaine significantly reduced the pain intensity and the increased skin blood flow only in men, but not women. The data demonstrate that gender-associated difference exists in HT saline intramuscularly induced local muscle pain and vasomotor responses. Neural mechanisms underlying gender-related differences in vasomotor responses is significantly different, suggesting that local pre-treatment, but not post-treatment, with anesthetic may provide superior analgesia to block sex-associated difference in pain and vasomotor responses.
本研究旨在探讨在肌肉内（i.m.）高渗（HT，5.8%）盐水引起肌肉疼痛的情况下，性别在疼痛和皮肤血管运动反应中的作用。在 20 名健康的人类受试者（10 名女性）中，将 2-4.8ml 的 HT 或等渗（IT，0.9%）盐水注入左胫骨前肌以引起肌肉疼痛，在此期间，研究了疼痛的强度和分布以及皮肤血管运动反应。使用激光多普勒血流仪评估 4 个不同皮肤区域的皮肤血流：同侧输注区域（5cm×5cm）、同侧牵涉痛区域（5cm×10cm）、输注部位对侧区域（5cm×5cm）和牵涉痛部位对侧区域（5cm×10cm）。在不同的 i.m. 输注中，4.8ml HT 盐水在不同受试者中引起最高的疼痛强度、最长的疼痛持续时间和最大的疼痛分布区域（P<0.001）。在 i.m. HT 盐水输注后观察到性别相关的疼痛和皮肤血管运动反应差异，但 IT 盐水输注后没有观察到差异，而女性表现出更强的疼痛强度和持续时间（P<0.001），并且在输注区域和对侧镜像区域表现出更多的血管运动反应（P<0.05）。在输注区域预先用 1ml 2%利多卡因预处理可显著减轻男性和女性的肌肉疼痛并阻断皮肤血流量的增加（P<0.05）。然而，利多卡因的后处理仅在男性中显著降低疼痛强度和增加皮肤血流量，但在女性中没有。数据表明，HT 盐水 i.m. 诱导的局部肌肉疼痛和血管运动反应存在性别差异。血管运动反应的性别相关差异的神经机制明显不同，表明局部预处理（而不是后处理）麻醉可能提供更好的镇痛效果，以阻断疼痛和血管运动反应中的性别差异。
