A Common NMDA- Dependent Mechanism in the Reconsolidation of the Stress and Cocaine-Induced Reinstatement of Extinguished Cocaine-Induced Conditioned Place Preference in rats
De Giovanni, L N;1 Virgolini, M B1, Cancela, L M.1
1 IFEC. CONICET. Departamento de Farmacología.Facultad de Ciencias Químicas. UNC.Córdoba. Argentina
Previous results from our lab showed that, the NMDA antagonist MK 801 abrogated the development and the expression of the stress-induced reinstatement (SR), in extinguished cocaine-induced conditioned place preference (CPP) rats, and that this was context-dependent and persistently observed on a subsequent cocaine-induced reinstatement (CR). Our goal was to determine if a common glutamatergic mechanism could be involved in the reconsolidation memory process on SR and CR. Male Wistar rats (220-300g) were conditioned with cocaine (10 mg/kg ip) during four alternated drug/vehicle sessions and later extinguished with successive vehicle associations. The following day, all groups of animals were reactivated in the CPP and, immediately or 3 h after the test, injected with either MK 801 (0.1 mg/kg ip) or vehicle, and 3 days after evaluated for a vehicle test. In the reinstatement day, 24 h after the vehicle test, the animals were randomly assigned to two experiments: 1) SR: animals were exposed or not to 30 min-immobilized, and 2) CR: animals were administered either a priming dose of cocaine (5 mg/kg ip) or vehicle. Immediately after, animals were tested in the CPP MK 801 administered immediately after the reactivation, but not after 3 h, blocked both, the SR and the CR. The prevention of SR and CR by the NMDA antagonism immediately after the reactivation could be attributed to a disruption of the reconsolidation memory process of the cocaine-induced CPP. These results further support an interchangeability in the mechanisms underlying the stress- and cocaine-induced reinstatement
Financial support: CONICET, FONCyT and SeCyT
