Low intensity laser therapy effectiveness in controlling neuropathic pain in mice

ABSTRACT Low-level laser therapy (LLLT) has been widely discussed in the literature as an alternative form of treatment for several types of pain, especially neuropathic pain. This kind of therapy stands out for not being invasive, rarely causing side effects and being cost effective. However, for its effectiveness, it is necessary more detailed parameters, which are still very discrepant in the literature. Thus, this study aims to investigate the effect of LLLT, in the infrared range, with 30J/cm² fluency, on the control of neuropathic pain in animal models. A total of 24 male Swiss albino mice, weighing 25.30 grams, were divided into three groups: the Control Group (CG), the Laser Group (L30G) and the Sham Group (SG). The induction of neuropathy was held through the model of chronic constriction of the sciatic nerve (CCI), and the LLLT treatment was conducted as follows: The CG was treated with 0 J/cm2 fluency, whereas the L30G was treated with 30 J/cm2 fluency, and the SG with simulation of surgery without intervention. The irradiations were performed 3 times a week, for 90 days, at the nerve’s point of compression, using the contact technique. For the evaluation, the Hot Plate Test was used for thermal hyperalgesia, and the Randall-Selitto test was used for mechanical hyperalgesia. In the CG’s results, we observed no significant improvement in the days after surgery in any of the tests conducted, and, in the GL30, a significant improvement in both tests was observed: from the 30th day of treatment for the Hot Plate Test, and from the 45th for the Randall-Selitto Test, in which the mice showed total restoration of sensitivity. We thus conclude that the use of LLLT with 30 J/cm2 fluency in the treatment of neuropathic pain in animal models is effective.