Suppression of harmaline-induced tremor in rats by vagus nerve stimulation

We studied whether vagus nerve stimulation could suppress tremor in the har maline tremor model in the rat. Animals were chronically implanted with hel ical leads around the left vagus nerve and a disk-shaped electrode position ed subcutaneously in the dorsal neck. Harmaline-induced tremor was recorded on a physiograph while each animal received a sequence of five 20-minute t rials. Each trial consisted of five minutes of pre-stimulation baseline, fi ve minutes of vagus nerve stimulation, and ten minutes of post-stimulation, Vague nerve stimulation significantly suppressed harmaline-induced tremor. The suppressive effect was present within the first minute of stimulation and was reproducible across the five trials of the study. The results of th is study suggest that the central generator or expression of tremor in the harmaline animal model can be suppressed by vagus nerve stimulation.