Ernberg M, Lundeberg T, Kopp S
Department of Clinical Oral Physiology, Institute of Odontology, Box 4064, S-141 04, Huddinge, Sweden.
Pain. 2000 Mar;85(1-2):31-9. doi: 10.1016/s0304-3959(99)00233-x.
The aim of this study was to investigate the effect of injection of serotonin (5-HT) into the masseter muscle on pain and allodynia/hyperalgesia. Twelve female patients with fibromyalgia (FM) and 12 age-matched female healthy individuals (HI) participated in the study. The current pain intensity (CPI) and the pressure pain threshold (PPT) of the superficial masseter muscles were assessed bilaterally. 5-HT in one of three randomized concentrations (10(-3), 10(-5), 10(-7) M) or isotonic saline was then injected into either of the two masseter muscles in a double-blind manner. After the injections the CPI and PPT were recorded ten times during 30 min. The injections were repeated twice with the other concentrations of 5-HT after 1 and 2 weeks, respectively. In the FM-group there was a non-significant increase of CPI after injection that lasted during the entire 30-min period irrespective of whether 5-HT or saline was injected. Neither did the PPT change significantly. In the HI-group pain developed significantly after injection irrespective of whether 5-HT or saline was injected, but significantly more so after 5-HT at 10(-3) M than saline injection. CPI decreased quickly and then remained on a very low level for most of the experiment. 5-HT at both 10(-5) M and 10(-3) M caused a significantly greater decrease of PPT than saline. In conclusion, our results show that 5-HT injected into the masseter muscle of healthy female subjects elicits pain and allodynia/hyperalgesia, while no such responses occur in patients with fibromyalgia.
本研究旨在探讨向咬肌注射5-羟色胺（5-HT）对疼痛及异常性疼痛/痛觉过敏的影响。12名患有纤维肌痛（FM）的女性患者和12名年龄匹配的健康女性个体（HI）参与了该研究。双侧评估咬肌浅层的当前疼痛强度（CPI）和压痛阈值（PPT）。然后以双盲方式将三种随机浓度（10^(-3)、10^(-5)、10^(-7) M）之一的5-HT或等渗盐水注射到两块咬肌中的任意一块。注射后，在30分钟内记录10次CPI和PPT。分别在1周和2周后用其他浓度的5-HT重复注射两次。在FM组中，注射后CPI有不显著的增加，在整个30分钟期间持续存在，无论注射的是5-HT还是盐水。PPT也没有显著变化。在HI组中，无论注射的是5-HT还是盐水，注射后都会出现显著疼痛，但在注射10^(-3) M的5-HT后比注射盐水时更显著。CPI迅速下降，然后在实验的大部分时间内保持在非常低的水平。10^(-5) M和10^(-3) M的5-HT导致PPT的下降比盐水显著更大。总之，我们的结果表明，向健康女性受试者的咬肌注射5-HT会引发疼痛和异常性疼痛/痛觉过敏，而纤维肌痛患者则不会出现这种反应。
