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Evidence-Based Complementary and Alternative Medicine
Volume 2014, Article ID 485043, 7 pages
Research Article

Electroacupuncture Reduces Hyperalgesia after Injections of Acidic Saline in Rats

1Graduate Program in Health Science, Federal University of Sergipe, Aracaju, SE, Brazil
2Graduate Program in Physiological Science, Federal University of Sergipe, Aracaju, SE, Brazil
3Department of Physical Therapy, Federal University of Sergipe, Aracaju, SE, Brazil
4Department of Physiology, Federal University of Sergipe, Aracaju, SE, Brazil

Received 10 September 2013; Revised 27 January 2014; Accepted 6 February 2014; Published 19 March 2014

Academic Editor: Cun-Zhi Liu

Copyright © 2014 Leonardo Yung dos Santos Maciel et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background. Injections of acidic saline into the gastrocnemius muscle in rats produce a bilateral long-lasting hyperalgesia similar to fibromyalgia in humans. No previous study investigated the effect of electroacupuncture (EA) on this acidic saline model. This study aimed to identify the effects of EA in the hyperalgesia produced by repeated intramuscular injections of acidic saline. Methods. Rats were divided into four groups ( , each group): control, acupuncture, EA 15 Hz, and 100 Hz. Left gastrocnemius muscle was injected with 100 μL of pH 4.0 sterile saline twice five days apart. EA, acupuncture, or control therapy was daily administered (20 min) for 5 consecutive days under anesthesia. Needles were placed in the St36 and Sp6 acupoints. The assessment of secondary mechanical hyperalgesia, thermal hyperalgesia, and motor performance was performed before injections and before and after the treatment performed on each day. The paw withdrawal threshold was tested using the nonparametric Kruskal-Wallis test and differences within the group Wilcoxon Matched Pairs. The latency and motor performance were tested for ANOVA parametric test for independent measures, and for differences in the group, we used -test for paired samples. Post hoc Tukey test was used for multiple corrections. values less than 0.05 were considered statistically significant. Results. Indicate that there was a significant reduction of mechanical withdrawal threshold and paw withdrawal latency 24 hours following the second injection. Moreover, mechanical and thermal hyperalgesia were significantly reversed by EA 15, 100 Hz, and acupuncture. Conclusions. The results suggest that EA high and low frequency as well as acupuncture are effective in reducing hyperalgesia in chronic muscle pain model.