Solitary tract nucleus sensitivity to moderate changes in glucose level

MANY neurons in the caudal nucleus tractus solitarii (NTS) recorded in vivo respond to moderate glycemic fluctuations through the local action of gluc ose molecules. To investigate this sensitivity in vitro, the extracellular activity of 112 neurons was recorded in hindbrain slices: 57 changed in fir ing rate when the glucose level in the bathing medium was increased by 2mM. Since the glucose-responding neurons were located in catecholaminergic reg ions and depressed by the alpha-2 adrenoceptor agonist clonidine, they were likely to be adrenergic or noradrenergic. A comparison of the responses to glucose and 2-deoxy-D-glucose suggested that the bioenergetic metabolism i s involved in NTS sensitivity to glucose. (C) 1999 Lippincott Williams & Wi lkins.