title: Effects of threonine injections in the lateral hypothalamus on intake of amino acid imbalanced diets in rats.
abstract: Previous work from this laboratory suggests that animals decrease their intake of an amino acid imbalanced diet (IMB), due in part to a drop in the concentration of the dietary limiting amino (DLAA) in the anterior piriform cortex (APC). Administration of the DLAA, but not of a non-limiting amino acid into the APC, blocks the anorectic response to IMB. To our knowledge, the effects of DLAA injections on intake of a diet devoid of the DLAA (DEV), have not been examined in areas outside the APC. We hypothesized that the LH is a potential chemosensory area for DLAA. Our objectives were: (1) to determine whether injections of the DLAA threonine into the lateral hypothalamus (LH) alter intake of a threonine-devoid diet (DEV); and (2) to examine the dose-response effects of threonine injections into the LH on intake of threonine-corrected diet (COR). Administration of threonine into the LH stimulated DEV intake during the first 6 h at the 0.25 and 1-nmol doses by approximately 26 and 24%, respectively. Threonine (0.25, 2.5 nmol) did not alter COR intake at any time during the first 12 h. Our results suggest that: (1) the LH, along with the APC, likely acts as a chemosensory brain area for indispensable amino acids; and (2) both the APC and LH are part of a circuit that is involved in the short term anorectic response to amino acid imbalanced diets.
authors.affiliation: Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, and Food Intake Laboratory, University of California, Davis, CA 95616, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Blevins
authors.forename: K D
authors.initials: KD
authors.lastname: Dixon
authors.forename: E J
authors.initials: EJ
authors.lastname: Hernandez
authors.forename: J A
authors.initials: JA
authors.lastname: Barrett
authors.forename: D W
authors.initials: DW
authors.lastname: Gietzen
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D000855:Anorexia; D004032:Diet; D002149:Energy Intake / Q000187:drug effects*; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008845:Microinjections; D009928:Organ Specificity; D051381:Rats; D017207:Rats, Sprague-Dawley; D013912:Threonine / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D013912:Threonine