Anxiolytic-like effect induced by chronic stress is reversed by naloxone pretreatment

CANCELA, L.M.; BREGONZIO, C.; MOLINA VICTOR ALEJANDRO

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1995 vol. 36 p. 209 - 209

he present study assesses the influence of different restraint schedules on behavioral parameters determined by a conflict test, namely the light- dark transitions (LDT) as well as the opiate modulation on the behavioral consequences induced by chronic restraint. Finally, another group of animals that received naloxone (NAL) and/or chronic stress was either exposed to a single foot shock session or administered a single dose of the β-carboline FG 7142 (N'-methyl-β-carboline-3-carboxamide) immediately prior to the LDT test. We observed that a single restraint session (2 h) induced a decrease of LDT and time spent in the lit box, while chronic restraint (2 h per day for up to 7 days) induced a significant increase in both parameters. However, this increasing effect was blocked by a NAL administration (2 mg/kg IP) prior to each of the seven restraint events. A single foot shock or FG administration produced a clear anxiogenic response, an effect that was absent in animals previ