ORIGINAL ARTICLE: Vagus nerve stimulation modulates cataplexy in narcoleptic dogs

The chronic effects of vagus nerve stimulation (VNS) on the occurrence of cataplexy and on the cataplexy modulating effects of central noradrenergic compounds (desipramine and BHT-950), were examined in two genetically narcoleptic dogs. In one dog, VNS significantly aggravated cataplexy with 0.5 mA of current and 500 mu s of pulse width. In the second dog, VNS tended to improve cataplexy with 1.5 mA of current and 250 mu s of pulse width (stimulation was applied for 30 s every 5 min and the frequency was 20 Hz in both dogs). The VNS had no effect on the cataplexy-suppressing effect of desipramine (a noradrenergic uptake inhibitor), while the cataplexy-aggravating effect of BHT-920 (an alpha-2 agonist) was attenuated by VNS in both dogs. It is therefore suggested that VNS modulates the central adrenergic neurotransmission and modifies cataplexy in the canine model of narcolepsy.