Basal and glucoprivic-induced changes in extracellular gaba in the
ventral hypothalamus of zucker rats.
Specter, S. E., B. A. Horwitz, and J. Lee Beverly.
Dept. of Nutrition, 2Section of Neurobiology, Physiology, and
Behavior - Division of Biological Sciences, University of California
Davis, CA 95616, and 3Dept. of Nutrition (ENRHM), Texas Tech
University Lubbock, TX 79409
APStracts 3:0075R, 1996.
The diminished sensitivity of genetically obese (fa/fa) Zucker rats to
the glucoprivic agent 2-deoxyglucose (2-DG) may involve impaired
release of the neurotransmitter g-aminobutyric acid (GABA) in
discrete regions of the hypothalamus. Extracellular GABA
concentrations in the medial (MH) and lateral hypothalamus (LH) of
lean (Fa/Fa) and age-matched obese (fa/fa) male Zucker rats before
and after 2-DG (1.2 mmoles/kg, i.v.). Basal GABA concentrations were
higher (p<0.05) in the MH of obese vs. lean rats. No differences
were noted in LH GABA levels between lean and obese rats or in
baseline extracellular GABA levels between brain regions in lean
rats. In lean rats, a characteristic bimodal increase in GABA
concentrations was apparent in the MH while GABA concentrations
decreased in the LH during the 60 min following 2-DG. No changes in
GABA concentrations in dialysate from the MH or LH of obese rats were
observed after 2-DG. The alterations in basal activity and
responsiveness to glucorpivic stimuli by GABAergic system in the MH
of obese rats may reflect a defect in central glucostatic control of
food intake and, ultimately, to the hypothesized autonomic imbalance
in fa/fa Zucker rat.
Received 27 September 1995; accepted in final form 23 February
1996.
APS Manuscript Number R608-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96