Extracellular glutamate increases in the lateral hypothalamus during meal initiation, and GABA peaks during satiation: microdialysis measurements every 30 s.
Glutamate injected into the lateral hypothalamus can initiate eating, and gamma-aminobutyric acid (GABA) can stop it. This leads to the hypothesis that glutamate inputs are active at the beginning of a meal, and GABA is released at the end. To test this theory, the authors used microdialysis to sample glutamate and GABA simultaneously before, during, and after a meal. Food-deprived rats ate a meal of chow. Glutamate increased during the first third of the meal, then decreased to below baseline while the rats were still eating. GABA also increased at the start of the meal but continued rising and peaked during the last third of the meal. Glutamate may drive a hypothalamic system for eating, and GABA may oppose it.
Rada
Pedro
P
Laboratory of Behavioral Physiology, School of Medicine, University of Los Andes, Mérida, Venezuela.
Mendialdua
Ainhoa
A
Hernandez
Luis
L
Hoebel
Bartley G
BG
D000818:Animals; D005110:Extracellular Space / Q000378:metabolism; D005247:Feeding Behavior / Q000502:physiology*; D019793:Fluorescein / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D007026:Hypothalamic Area, Lateral / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012527:Satiation / Q000502:physiology*; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D019793:Fluorescein