تاثير تداخل گيرنده هاي موسكاريني و NMDA ناحيه تگمنتوم شكمي بر تثبيت حافظه اجتنابي مهاري

Effect of muscarinic and NMDA receptors of ventral tegmental area interaction on inhibitory avoidance memory consolidation

Aims: In the present study, the effect of intra-VTA post-training administration of a nonselective muscarinic antagonist, scopolamine and the drugs affecting N-methyl-D-aspartate (NMDA) receptors and their interaction in the inhibitory avoidance memory consolidation was investigated. Materials & Methods: Rats were anesthetized with intra-peritoneal injection of ketamine hydrochloride, plus xylazine and then placed in a stereotaxic apparatus. Two cannuales were placed 2 mm above ventral tegmental area. After a week, rats were trained in a passive avoidance learning unit and the drugs were injected after the successful training. The test was carried out 24h after the training and the animalʹs latency in entrancing to black box was measured as the memory criteria. One- and two-way analyses of variance (ANOVAs) followed by Tukeyʹs post hoc test, were used for analysis of the data. Results: Intra-VTA administration of scopolamine (1-2 (ig/rat) and MK-801 (0.75-1 (ig/rat) immediately after training decreased inhibitory avoidance memory on the test day. Co-administration of an ineffective dose of MK801 and scopolamine (0.25-0.5 (ig/rat) significantly decreased the inhibitory avoidance memory. Post-training intra-VTA injections of NMDA (0.01-0.001 (ig/rat) had no effect by itself, whereas its co-administration with scopolamine (2 |ig/rat) prevented the decreasing effect of scopolamine on inhibitory avoidance memory. Conclusion: Muscarinic acetylcholine and NMDA receptors are involved in the mechanism(s) modulating inhibitory avoidance memory. There is an interaction between muscarinic and NMDA receptors in the modulation of inhibitory avoidance memory consolidation in the ventral tegmental area.