ArticlesAn Improved Method for Assessing Mechanical Allodynia in the Rat
Section snippets
Materials and methods
Male Sprague–Dawley rats (250–350 g, Harlan, Indianapolis) were used. The rat was habituated to stand on its hind paws and lean against the experimenter's hand wearing a regular leather work glove (Fig. 1). Instead of standing on a meshed metal, or grid surface, the rat stands on a soft pad. The habituation required no more than normal petting of the rat, and it can be achieved within half an hour. The smell that developed on the glove through the handling of animals appeared to facilitate the
Results
During the test session, the rat was calm and exhibited normal grooming behavior. Occasional petting by the investigator ensured the rat to maintain its position. In most cases, the nociceptive response threshold was determined without interruption.
Discussion
The present study provides an improved and simple method for assessing the mechanical nociceptive threshold in naive rats and mechanical allodynia in CFA-inflamed rats. The key to this method is that although there was no restraining involved, the rat stays calmly in one place. The mechanical probes can be delivered to the targeted areas repeatedly. Because the animal was not walking during the testing, false responses due to random stepping were eliminated.
Compared to the plantar probing
Acknowledgements
The author thanks Dr. R. Dubner and Dr. J. D. Greenspan for critical reviewing of an earlier draft of this manuscript, and Ms. E. Wade and Ms S. Zou for technical assistance. This work was supported by DE 11964, DA10275.
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