Received: September 21, 2007.

Accepted: May 19, 2008.

Abstract published online: May 30, 2008.

Full paper published online: August 31, 2008.

THE EFFECTS OF LOW-LEVEL LASER ON MUSCLE DAMAGE CAUSED BY Bothrops neuwiedi VENOM

DOURADO DM (1), MATIAS R (1), ALMEIDA MF (1), DE PAULA KR (1), VIEIRA RP (3), OLIVEIRA LVF (2), CARVALHO PTC (1)

(1) Laboratory of Experimental Histopathology, University for the Development of the State and of the Region of Pantanal, UNIDERP, Campo Grande, Mato Grosso do Sul State, Brazil; (2) Masters Program in Rehabilitation Sciences, Nove de Julho University, UNINOVE, São Paulo, São Paulo State, Brazil; (3) Department of Pathology and Physical Therapy, School of Medicine, University of São Paulo, São Paulo, São Paulo State, Brazil.

ABSTRACT: The present study aimed to assess the effects of low-level laser (660 nm) on myonecrosis caused by the insertion of Bothrops neuwiedi venom in the gastrocnemius muscle of rats. Male Wistar rats were divided into three groups (n = 24 each): Group S (0.9% saline solution); Group V (venom) and Group VLLL (venom plus low-level laser). These categories were subdivided into four additional groups (n = 6) based on the euthanasia timing (3 hours, 24 hours, 3 days and 7 days). The groups V and VLLL were inoculated with 100 µL of concentrated venom (40 µg/mL) in the gastrocnemius muscle. The muscle was irradiated using a gallium-aluminum-arsenide laser (GaAlAs) at 35 mW power and 4 J/cm² energy density for 3 hours, 24 hours, 3 days or 7 days after venom inoculation. To evaluate the myotoxic activity of the venom, CK activity was measured and the muscle was histologically analyzed. The low-level laser reduced venom-induced CK activity in the groups euthanized at 3 hours, 24 hours and 3 days (p < 0.0001). Histological analysis revealed that low-level laser reduced neutrophilic inflammation as well as myofibrillar edema, hemorrhage and myonecrosis following B. neuwiedi envenomation. These results suggest that low-level laser can be useful as an adjunct therapy following B. neuwiedi envenomation.

KEY WORDS: myonecrosis, B. neuwiedi venom, low-level laser.

CONFLICTS OF INTEREST: There is no conflict.

CORRESPONDENCE TO:

DOROTY MESQUITA DOURADO, Rua Ceara, 333, Bairro Miguel Couto, Campo Grande, MS, 79032423, Brazil. Phone: +55 67 33488366. Email: ccfi@uniderp.br.