Effect of intra-core, but not intra-shell, mGlu II agonist administration in restraint stress-induced reinstatement on extinguished cocaine conditioned animals

DE GIOVANNI, LN; VIRGOLINI, MB; CANCELA, LM

Concepcion

Workshop; INTERNATIONAL WORKSHOP First Joint Meeting Alcohol and other Drugs of Abuse: from molecules to human disorders; 2013

LARNEDA-LASBRA

  Previous results from our lab showed that the intra-core administration of an NMDA receptor antagonist, MK 801, blocked the stress-induced reinstatement in extinguished cocaine-induced conditioned place preference (CPP) in rats. Several studies suggest that group II metabotropic glutamatergic receptors (mGlu II), are involved in cocaine reward so, the goal of the current study was determine if that receptors exert an influence in restraint-stress induced reinstatement. In the present experiments, our goal was to determine if the intra-core vs. intra-shell administration of LY 479234 (mGlu II agonist) could influence the stress-induced reinstatement. Male Wistar rats (220-300g) were conditioned with cocaine (10 mg/kg i.p.) during four alternated drug/vehicle sessions, and later extinguished with successive vehicle associations. The following day, animals were microinfunded, intra-core or intra-shell, with LY 479234 (0.5 ug/side) or vehicle and 5 min later exposed to a 30 min restraint-stress session (Stress animals) or left undisturbed in their home-cages (Non-Stress animals). Results demonstrate that, the intra-core administration of LY 479234 blocked the restraint stress-induced reinstatement, while the intra-shell administration did not exert any influence. The current results support the hypothesis of the specific participation of mGlu II receptors of Nucleus Accumbens Core how a possible mechanism to understand stress-triggered reinstatement in extinguished cocaine-conditioned animals.  Financial Support: FONCYT, Ministerio de Ciencia y Tecnología, CONICET and SECyT