GALANIN-CONTAINING NEURONS IN THE PARAVENTRICULAR NUCLEUS - A NEUROCHEMICAL MARKER FOR FAT INGESTION AND BODY-WEIGHT GAIN

The physiological function of the peptide galanin (Gal) remains to be established. It is known to exist in high concentrations within the hy pothalamus and to modulate the secretion of specific hormones, as well as to potentiate food consumption. Our study provides evidence for an essential function of neuronal Gal, within a specific hypothalamic ar ea, in stimulating the behavioral process of fat ingestion and body we ight gain. Through analyses of peptide levels via RIA and of gene expr ession via in situ hybridization, a close positive association is esta blished between Gal in the paraventricular nucleus (PVN), particularly its midlateral region, and fat ingestion. No such relationship is det ected for Gal in other brain areas or between PVN Gal and ingestion of carbohydrate or protein, supporting the behavioral and anatomical spe cificity of this relationship. Through PVN injection studies with anti sense oligonucleotides to Gal mRNA, a dramatic decline in fat ingestio n and body weight suggests that endogenous Gal contributes to the natu ral appetite for fat. Thus, Gal in the PVN is identified as a neuroche mical marker for fat ingestion and, consequently, body weight gain.