ArticlesPost-operative pain behavior in rats is reduced after single high-concentration capsaicin applicationPospisilova, Eva; Palecek, Jiri*Author Information Department of Functional Morphology, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic *Corresponding author. Tel.: +420 2 4106 2664; fax: +420 2 4106 2488. E-mail address:firstname.lastname@example.org Submitted January 27, 2006; revised May 4, 2006; accepted May 22, 2006. Pain: December 2006 - Volume 125 - Issue 3 - p 233-243 doi: 10.1016/j.pain.2006.05.021 Buy Metrics Abstract Surgical procedures associated with tissue injury are often followed by increased sensitivity to innocuous and noxious stimuli in the vicinity of the surgical wound. The aim of this study was to evaluate the role of transient receptor potential vanilloid 1 receptor (TRPV1) containing nociceptors in this process, by their functional inactivation using a high-concentration intradermal injection of capsaicin in a rat plantar incision model. Paw withdrawal responses to mechanical stimuli (von Frey filaments 10–367 mN) and to radiant heat applied on plantar skin were tested in animals treated with capsaicin or the vehicle 6 days and 24 h before or 2 h after the incision was made. In the vehicle-treated animals, mechanical and thermal sensitivity increased significantly 1–96 h following the incision. Capsaicin applied 24 h before the surgery was most effective and significantly diminished the development of post-incisional mechanical allodynia and hyperalgesia. Thermal hypoalgesia was present in the incised paw after the capsaicin treatment. Capsaicin application 6 days before the incision induced thermal hypoalgesia before the incision but did not prevent completely the thermal hyperalgesia after the incision, while there was also a reduction of mechanical hypersensitivity. Application of the capsaicin injection after the incision showed its first effect at 2 h after the injection and at 24 h the effect was comparable with the 6 days pretreatment. Our results show an important role of TRPV1-containing nociceptors in the development of post-surgical hypersensitivity and suggest that local, high-concentration capsaicin treatment could be used to reduce it. © 2006 Lippincott Williams & Wilkins, Inc.