title: Fear and feeding in the nucleus accumbens shell: rostrocaudal segregation of GABA-elicited defensive behavior versus eating behavior.
abstract: This study examined localization of positive versus negative motivational functions mediated by GABA circuits within the accumbens shell. Microinjections of a GABA(A) agonist (0, 25, 75, and 225 ng/0.5 microl muscimol) in rostral shell sites elicited appetitive increases in eating behavior. In contrast, microinjections in caudal shell sites elicited defensive burying or paw-treading behavior. Rats whose microinjections landed bilaterally outside of the accumbens shell did not display either behavior. Defensive treading elicited by caudal shell muscimol microinjection appeared to be a negative motivated response to threat (similar in parameters and orientation to normal defensive burying of a threatening electrified shock prod). The nucleus accumbens shell thus appears functionally heterogeneous in coding motivational valence. The demonstration that muscimol elicits positive eating behavior from rostral shell versus negative defensive behavior from caudal shell suggests in particular that GABAergic substrates of positive and negative types of motivated behavior in the nucleus accumbens shell are segregated along a rostrocaudal gradient.
authors: Department of Psychology, University of Michigan, Ann Arbor, Michigan 48109, USA. sheilar@umich.edu
authors: S M
authors: SM
authors: Reynolds
authors: K C
authors: KC
authors: Berridge
mesh_terms: D000374:Aggression / Q000187:drug effects / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects / Q000502:physiology; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D004597:Electroshock; D005239:Fear / Q000187:drug effects / Q000502:physiology*; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D018755:GABA Agonists / Q000008:administration & dosage; D008845:Microinjections; D009042:Motivation; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009118:Muscimol / Q000008:administration & dosage; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism*; D009949:Orientation / Q000187:drug effects / Q000502:physiology; D051381:Rats; D005680:gamma-Aminobutyric Acid / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D018755:GABA Agonists; D009118:Muscimol; D005680:gamma-Aminobutyric Acid