Feeding modulation by pentose and hexose analogues

Abstract

D-Glucosamine (GlcN), N-acetyl-D-glucosamine (GlcNAc) and 2,5-anhydro-D-mannitol (2,5-AM) were infused into the rat third cerebroventricle (icv) to compare their effects on food intake. GlcN (24 mumols/L) accelerated eating, and concomitantly increased plasma glucose, free fatty acids, and glycerol without affecting plasma insulin. GlcN accelerated lateral hypothalamic (LHA), and reciprocally decreased ventromedial hypothalamic (VMH) neuronal activity. Infusion of 12 mumols GlcNAc icv did not affect feeding, but oral administration (1200 mumols/L) induced feeding. The GlcNAc-induced feeding was completely abolished by bilateral truncal vagotomy. Infusion of 2,5-AM dose-dependently induced feeding (P less than 0.01). A maximal dose (24 mumols/L) did not substantially change plasma glucose or insulin. Unilateral 2,5-AM microinfusion (1.2 mumols/L) into the VMH, but not into the LHA, elicited feeding. The characteristic actions of these analogues are useful to clarify central control of food intake and also as probes to examine relations between feeding modulation and energy metabolism in the central nervous system.