Modulation of brain dead induced inflammation by vagus nerve stimulation

Because the vagus nerve is implicated in control of inflammation, we investigated if brain death causes impairment of the parasympathetic nervous system, hence contributing to inflammation. Brain death (BD) was induced in rats. Anaesthetised ventilated rats (NBD) served as control. Heart rate variability (HRV) was assessed by ECG. The vagus nerve was electrically stimulated (BD+STIM) during BD. Intestine, kidney, heart and liver were harvested after 6h. Affymetrix chip- analysis was performed on intestinal RNA. Quantitative PCR was performed on all organs. Serum was collected to assess TNFα concentrations. Renal transplantations were performed to address the influence of vagus nerve stimulation on graft outcome. HRV was significantly lower in BD animals. Vagus nerve stimulation inhibited the increase in serum TNFα concentrations and resulted in down-regulation of a multiplicity of pro-inflammatory genes in intestinal tissue. In renal tissue vagal stimulation significantly decreased the expression of E-selectin, IL1β and ITGA6. Renal function was significantly better in recipients that received a graft from a BD+STIM donor. Our study demonstrates impairment of the parasympathetic nervous system during BD and inhibition of serum TNFα through vagal stimulation. Vagus nerve stimulation variably affected gene expression in donor organs and improved renal function in recipients. Gene expression in brain dead (BD) induced rat (with and without vagal stimulation) was compared with that of Non brain-dead ventilated control (NBD)