THE NMDA ANTAGONIST, MK 801, BLOCKS THE EXPRESSION OF STRESS-INDUCED REINSTATEMENT
De Giovanni, Laura Noemi; Virgolini, Miriam Beatriz, Cancela, Liliana Marina.
luli_deyo@yahoo.com.ar
Recent studies of our laboratory demonstrate that the NMDA antagonist MK 801 given 15 min before the a single stress session of 30 min induce a long lasting blockage in the stress-induce reinstatement and in the subsecuents cocaine-induce reinstatement 3 and 10 days after the first reinstatement , in animals previously conditioned with cocaine. Besides, we demonstrate that MK 801 by itself induce reinstatement in the first reinstatement test, but 3 and 10 days after show blockage in the subsequent cocaine-induce reinstatement, supporting the idea that MK 801 blocks the reinstatement induced by stress , cocaine and context. In order to demonstrate that the effect of MK 801 is specific and is not a effect anxiolytic on stress, Male wistar rats was conditioned and then extinguished following the CPP reinstatement procedure, in the reinstatement day the animals were separated in two diferents groups , with or without a single stress session of 30min. After that the animals come back at their homecage and receive MK 801 (0.1 mg/kg) or VEH and 15 min later were tested in the CPP. We demonstrate that all the animals that receive MK 801 shows blockage in the stress or context -induce reinstatement and in the subsequent cocaine-induce reinstatement.
These results support the hypothesis that the blockage induced by MK 801 is a specific effect on the reward pathway and this blockage is long lasting 3 and 10 days in response to a priming dose of cocaine , given more evidence to neurobiological shared mechanism between cocaine and stress in the reinstatement.
