Lateral hypothalamic injection of 2-deoxy-D-glucose suppresses sympathetic activity

To investigate the effects of glucoprivation on sympathetic nerve activity to interscapular brown adipose tissue (IBAT), 2-deoxy-D-glucose (2-DG) was injected into the third cerebral ventricle (icv), lateral hypothalamic area (LHA), and ventromedial hypothalamic nucleus (VMN) of rats. The multiunit discharges of sympathetic nerves to IBAT were recorded electrophysiologically. The icv injection of high and low doses of 2-DG (5.0 and 2.5 mg/rat) suppressed sympathetic nerve activity by 76.9 and 49.8% respectively, 30 min after injection compared with preinjected base line. After the low dose of 2-DG, there was a gradual recovery, but after the high dose recovery did not occur. The unilateral microinjection of 2-DG (0.25 mg/rat) into the LHA induced a similar suppression of sympathetic nerve activity to that observed after icv injection of 10 times as much 2-DG (-25.3%). The injection of vehicle or sucrose into the LHA did not suppress sympathetic nerve activity. The microinjection into the VMN either unilaterally or bilaterally did not suppress sympathetic nerve activity to IBAT. We conclude that the LHA but not the VMH is one site of action of 2-DG. The data are consistent with the hypothesis that the brain senses glucoprivation in the LHA and reduces sympathetic drive to thermogenic tissues such as IBAT.