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Abstract
Low-level laser therapy (LLLT) in acupuncture is a low-power laser applied to acupoints for providing luminous energy, capable to produce photobiological induction that results in biochemical, bioelectric, and bioenergetic effects. ST36 (Zusanli) is a point of acupuncture commonly used for treatment of several pathological alterations, such as inflammation, acute pain, and gastrointestinal disorders. In this study, we evaluated the anti-inflammatory effect of LLLT (830 nm, 4 J/cm^sup 2^) in ST36 acupoint through the model of carrageenan-induced paw edema in mice and the possible mechanisms involved. Female Swiss mice were treated with LLLT in ST36 before the paw edema induction, which was measured by means of a digital micrometer and the temperature through a high-resolution digital thermograph. After this, the levels of reactive oxygen species (ROS), lipid hydroperoxides (LOOH), and reduced glutathione (GSH) were quantified. In another set of experiments, the paw edema was induced by bradykinin, histamine, and prostaglandin E^sub 2^ (PGE^sub 2^). LLLT in ST36 acupoint significantly inhibited the edema formation for 4 h after the carrageenan injection and reduced the paw temperature in 10 %. Furthermore, LLLT also reduced the levels of ROS (55 %) and LOOH (50 %) but, however, did not alter the GSH levels. LLLT in ST36 reduced the paw edema induced by bradykinin (30 min, 6 %, 60 min, 7 %), histamine (30 min, 11 %), and PGE^sub 2^ (90 min, 10 %, 120 min, 16 %). In conclusion, these results prove that LLLT in ST36 acupoint produces a relevant anti-inflammatory effect, reducing edema, temperature, and free radicals levels in mice paw.