<title>Analgesic effect of low-power infrared laser radiation in rats</title>

Abstract

The aim of the study was to confirm the analgesic effect of low-power laser radiation with a tail-immersion test and check if nitric oxide is involved in laser radiation-induced analgesia in rats. The experiment was performed on male Wistar rats. On the day of experiment the scull of rats was exposed to infrared laser radiation (wavelength 904 nm, mean power 8.9 mW) for 10 min and antinociceptive effect was determined by means of tail immersion test. The experiments were also performed on 1-NAME (N-nitro-L-arginine methyl ester 100 nmols icv.) and methylene blue (100 nmols icv.) pretreated rats, in which both chemicals were administered into right lateral brain ventricle. The results were compared to the ones obtained in the control group in which sham irradiation was made. It was observed that 10 min. exposure to low-power infrared laser radiation induced only transient distinct antinociceptive effect in rats (in the last phase of irradiation. This effect was prevented by icv. injection of 1-NAME, an inhibitor of nitric oxide synthase and methylene blue, an inhibitor of soluble guanylate cyclase. It seems that nitric oxide is involved in mechanism of low-power laser radiation-induced analgesia.