Convergence of pre- and postsynaptic influences on glucosensing neurons in the ventromedial hypothalamic nucleus

Abstract

Glucosensing neurons in the ventromedial hypothalamic nucleus (VMN) were studied using visually guided slice-patch recording techniques in brain slices from 14- to 21-day-old male Sprague-Dawley rats. Whole-cell current-clamp recordings were made as extracellular glucose levels were increased (from 2.5 to 5 or 10 mmol/l) or decreased (from 2.5 to 0.1 mmol/l). Using these physiological conditions to define glucosensing neurons, two subtypes of VMN glucosensing neurons were directly responsive to alterations in extracellular glucose levels. Another three subtypes were not directly glucose-sensing themselves, but rather were presynap-tically modulated by changes in extracellular glucose. Of the VMN neurons, 14 % were directly inhibited by decreases in extracellular glucose (glucose-excite