Role of vagus in mediating the toxicity induced by Mesobuthus tamulus venom in rats

Abstract

Background: Mesobuthus tumulus (red scorpion, MBT) envenomation is a serious health problem in tropical countries and is responsible for high morbidity and mortality. Aims and Objectives: Earlier reports about the role of vagus in producing MBT venom-induced toxicity are conflicting. Therefore, in this study, the role of vagus in MBT venom-induced toxicity in rats was evaluated. Materials and Methods: The rats were divided into three groups. In group I, only saline was injected. This group served as control. In group II, MBT venom was injected. In group III, MBT venom was injected in vagotomized rats. Mean arterial pressure (MAP), ECG (for heart rate [HR]), respiratory rate, pulmonary water content, and survival time were determined in all groups. Results: Exposure to MBT venom in rats produced prolonged apnea with intermittent shallow breathing and was accompanied by an instantaneous decrease, followed by an increase and then a progressive decrease in MAP and HR leading to death within 60 min. There was increased pulmonary water content (82% vs. 74% in controls). MBT venom in vagotomized rats produced immediate changes as before, but these changes recovered to reasonably good level within 30 min and the animals survived for >120 min. Pulmonary water content in vagotomized rats was similar to control group. Conclusion: The results indicate that vagus plays a vital role for the toxic effects produced by MBT venom.