Abstracts

Rationale: Vagus nerve stimulation (VNS) is widely used as a palliative surgical therapy for patients with intractable epilepsy, although its working mechanism is not well understood.Methods: In this study, the left vagus nerve was stimulated for 2 h (one burst of 20 Hz with 250-msec pulse-width of 2.0-mA output current for 30 sec every 5 min) in 8 conscious rats, while 8 other rats served as controls. Then, we quantified c-Fos expression as biomarkers of short-term neuronal activation to identify potential site in rat brains where VNS may produce its clinically significant effects. Data from the cell counts were analyzed by the Mann-Whitney U-test for each area of brain in all groups.Results: The results showed that while VNS significantly increased c-Fos staining bilaterally in the nucleus of solitary tract (NTS: P= 0.003), paraventricular thalamic nucleus (PVP: P=0.040), central medial nucleus (CM: P=0.010), bed nucleus of stria terminalis (BST: P=0.028), and the lateral septal nucleus (LSV: P=0.002), only a trend of greater c-Fos expression in the locus caeruleus (LC: P=0.054) was noted.Conclusions: The LC and CM belong to the ascending arousal system. The BST and the LSV are connected to the limbic system; these systems may collectively play an important role in the VNS mechanism of suppressing intractable epilepsy.