GLUCOSE-SENSITIVE NEURONS OF THE GLOBUS-PALLIDUS .1. NEUROCHEMICAL CHARACTERISTICS

The lateral hypothalamic area (LHA) and globus pallidus (GP) are basic ally involved in the regulation of feeding and metabolic processes. In the LHA, glucose-sensitive (GS) neurons were described: their activit y was found to be specifically suppressed by electrophoretic applicati on of glucose, and these neurons appeared to be also influenced by var ious feeding-associated neurochemical signals. The main goal of the pr esent experiments was to examine whether similar GS neurons exist in t he GP. In addition, neurochemical attributes of the cells were also te sted. In anesthetized rats and anesthetized or awake monkeys, single-n euron activity of the GP was recorded by means of carbon fiber multiba rreled microelectrodes and the effects of glucose, glutamate (Gt), GAB A, dopamine (DA), noradrenaline (NA) and acetylcholine (Ach) were stud ied. In both the rat and monkey GP, approximately 12% of the neurons e xamined responded, with inhibition, to glucose. GP neurons, in a high proportion, were also inhibited by GABA and NA. After application of G t, DA, or Ach, activity increase or decrease occurred. GS neurons exhi bited remarkable sensitivity to these neurochemicals previously identi fied as neurotransmitters of the complex pallidal, extrapyramidal-limb ic neuron loops. The results, along with previous data, indicate that GS cells of the GP, while possessing complex neurochemical characteris tics, may belong to a hierarchically organized central glucose-monitor ing system essential in the regulation of feeding.