EFFECTS OF MUSCIMOL AND DIAZEPAM - COMPARATIVE-STUDY ON BEHAVIORAL-INHIBITION INDUCED BY NOVELTY, PUNISHMENT, AND NONREWARD

Diazepam and muscimol, a direct GABA agonist, were compared on behavioral inhibition induced in rats by (1) novelty, (2) punishment, and (3) nonreward. (1) Muscimol (0.03-0.25 mg·kg-1 i.p. 30 min before testing, or i.v. immediately before testing) failed to enhance food intake consistently in a nonfamiliar situation and (0.125-0.5 mg · kg-1 i.p. or i.v.) to increase the ingestion of an unknown food (chocolate); (2) muscimol (0.125-0.5 mg · kg-1 i.p. or 0.25 i.v. 10 min before testing) was ineffective in reducing the inhibition of lever presses for food elicited by the delivery of an electric shock at every eighth press; (3) muscimol (0.125-0.5 mg · kg-1 i.p.) failed to attenuate the inhibitory effects on responding induced by the suppression of the reinforcement during extinction. Contrastingly, diazepam (2 mg · kg-1 i.p. 30 min before testing) was found to reduce each type of behavioral inhibition. These data lend no support to the hypotheses of GABA control of behavioral inhibition and of GABA involvement in the action of benzodiazepines on inhibition induced by novelty, punishment, or nonreward. © 1979 Springer-Verlag.