TRANSIENT EMOTIONAL CHANGES ELICITED BY INTRAPERITONEAL SALINE INJECTION - EFFECT OF NALOXONE AND FLUMAZENIL

The effect of the intraperitoneal (IF) saline injection was assessed b y using the defensive burying (DB) and the elevated plus-maze (EPM) an xiety paradigms in rats. Animals were handled gently by the body, inje cted IP with saline solution, 2 ml/kg, and tested independently in the defensive burying as well as in the elevated plus-maze test at differ ent times after the LP injection: 1.5, 3, 5, 10, 15, and 30 min. A tra nsient effect of IP saline injection was observed (i.e., increased DB in animals tested 1.5 min after injection) and a decrease in this para meter when studied 3 min after the injection. No changes at 5, 10, 15, and 30 min after the injection were found. To discriminate the putati ve participation of the opiate peptide and benzodiazepine receptors in the actions of the IP injection, flumazenil (5 mg/kg) and naloxone (1 mg/kg) were administered. The increase in DB at 1.5 min was masked by double injection, an effect blocked by naloxone, but not by flumazeni l, while both of them reverted the decrease in DB response in animals tested 3 min after injection. A partial action of the IP in the animal s tested in the elevated plus-maze test was found. Present results are discussed on the basis of behavioral and pharmacological evidence. Co pyright (C) 1997 Elsevier Science Inc.