Low-intensity laser therapy improves tetanic contractions in mouse anterior tibialis muscle injected with Bothrops jararaca snake venom

Abstract Introduction Envenomation by Bothrops snakes can produce local pain, edema, hemorrhage and myonecrosis. However, standard antivenom therapy is generally ineffective in neutralizing these effects so that alternative methods of treatment have been investigated. In experimental animals, low-level laser therapy (LLLT) attenuates the local effects of Bothrops venoms, but the benefits of LLLT on muscle function after envenomation are unclear. In this study, we examined the influence of LLLT on the contractile activity of mouse skeletal muscle injected with venom from Bothrops jararaca, the principal cause of snakebite in southeastern Brazil. Methods Twenty-seven male mice were used. Mice were injected with venom (40 μg in 50 μl) in the right anterior tibialis muscle, after which the muscle tendon was exposed, connected to an isometric transducer and subjected to a resting tension of 1 g. A bipolar electrode was attached to the tibial nerve for electrical stimulation. The mice were randomly allocated to five groups: A – Control (n = 3), B – Venom 3 h (n = 6), C – Venom 9 h (n = 6), D – Venom + Laser 3 h (n = 6), E – Venom + Laser 9 h (n = 6). Results The two groups that received LLLT post-venom showed improved muscle contraction and contracture in relation to muscle treated with venom alone. Conclusion These results indicate that LLLT can improve muscle function after damage induced by B. jararaca venom.

摘要 引言
矛头蝮属（Bothrops）蛇类咬伤所致的中毒，可引发局部疼痛、水肿、出血及肌坏死。然而，标准抗蛇毒血清疗法通常无法中和此类局部损害，因此学界已探索多种替代治疗方案。在实验动物模型中，低强度激光疗法（low-level laser therapy, LLLT）可缓解矛头蝮蛇毒的局部毒性作用，但低强度激光疗法对中毒后肌肉功能的改善效果仍不明确。本研究以巴西东南部蛇咬伤的主要致病蛇种——巴西矛头蝮（Bothrops jararaca）的蛇毒注入小鼠骨骼肌内，探讨了低强度激光疗法对小鼠骨骼肌收缩功能的影响。
方法
本研究共使用27只雄性小鼠。向小鼠右侧胫骨前肌注射40 μg（溶于50 μl溶剂）的蛇毒，随后暴露肌肉肌腱，将其连接至等长张力换能器，并施加1 g的静息张力。将双极电极固定于胫神经以实施电刺激。将小鼠随机分为5组：A组为对照组（n=3），B组为毒液处理3小时组（n=6），C组为毒液处理9小时组（n=6），D组为毒液+低强度激光疗法3小时组（n=6），E组为毒液+低强度激光疗法9小时组（n=6）。
结果
与仅接受蛇毒处理的组别相比，蛇毒注射后接受低强度激光疗法干预的两个实验组，其肌肉收缩功能与挛缩程度均得到改善。
结论
本研究结果表明，低强度激光疗法可改善巴西矛头蝮蛇毒诱导的肌肉损伤后的肌肉功能。