A pharmacologic approach to vagal nerve stimulation prevents mesenteric lymph toxicity after hemorrhagic shock

Background: Electrical stimulation of the vagus nerve (VN) prevents gut and lung inflammation and mesenteric lymph (ML) toxicity in animal models of injury. We have previously shown that treatment with CPSI-121, a guanylhydrazone-derived compound, prevents gut barrier failure after burn injury. While the structure of CPSI-121 predicts that it will activate parasympathetic signaling, its ability to stimulate the VN is unknown. The aims of this study were to (1) measure the ability of CPSI-121 to induce VN activity, (2) determine whether CPSI-121 causes significant hemodynamic effects, and (3) further define the potential for CPSI-121 to limit the systemic inflammatory response to injury. Methods: Male Sprague-Dawley rats were given 1-mg/kg CPSI-121 intravenously while blood pressure, heart rate, and efferent VN electrical activity were recorded. Rats were also assigned to sham or trauma/hemorrhagic shock (T/HS). T/HS was induced by laparotomy and 60 minutes of HS (mean arterial pressure, 35 mm Hg) followed by fluid resuscitation. A separate cohort of animals received CPSI-121 after the HS phase. Gut and lung tissues were harvested for histologic analysis. Lung wet-dry ratios were also evaluated. The ability of ML to prime neutrophils was assessed by measuring in vitro oxidative burst using flow cytometry. Results: Blood pressure was not altered after treatment with CPSI-121, while heart rate decreased only slightly. Recording of efferent VN electrical activity revealed an increase in discharge rate after administration of CPSI-121. T/HS caused gut and lung injury, which were prevented in animals treated with CPSI-121 (p < 0.05). Treatment with CPSI-121 following T/HS attenuated neutrophil priming after exposure to ML (p < 0.05). Conclusion: CPSI-121 causes efferent VN output and limits shock-induced gut and lung injury as well as ML toxicity. CPSI-121 is a candidate pharmacologic approach to VN stimulation aimed at limiting the inflammatory response in patients following T/HS.