Inhibition of brown adipose tissue (BAT) and shivering thermogenesis by vagal nerve stimulation (VNS)

The dependence of thermogenesis on the availability of metabolic substrates suggests that vagally-transmitted, metabolic signals from the viscera could influence the central neural systems driving the BAT and shivering thermogenesis that normally contributes to the cold-defensive maintenance of core body temperature and to the elevated temperature during fever. We tested this hypothesis by electrically stimulating viscerosensory afferents in the proximal end of the sectioned cervical vagus nerve in Inactin-anesthetized, ventilated rats while recording BAT sympathetic nerve activity (SNA) and nucal EMG. Continuous VNS at 10Hz produced a complete inhibition of cold-evoked BAT SNA and shivering EMG activity. Similar inhibitions of BAT and shivering thermogenesis follow activation of neurons in the nucleus of the solitary tract (NTS) or those in the caudal ventrolateral medulla (cVLM). These data support the existence of populations of vagal afferents whose stimulation can inhibit the generation of BAT sympathetic and shivering EMG activities, perhaps via activation of thermogenesis-inhibiting neurons in the NTS and the cVLM (see Am. J. Physiol. Regul. Integr. Comp. Physiol., 299:R277-R290, 2010). Supported by NIH grants NS040987 and NS091066.