EFFECTS OF OXOTREMORINE ON INHIBITORY AVOIDANCE-BEHAVIOR IN 2 INBRED STRAINS OF MICE - INTERACTION WITH 5-METHOXY-NN-DIMETHYLTRIPTAMINE

The effects of the cholinergic muscarinic agonist, oxotremorine (0.005 , 0.01, 0.02 and 0.04 mg/kg), the serotonergic agonist, 5-methoxy-NN-d imethyltriptamine (5-MeODMT) (0.5, 1 and 2 mg/kg), and their combinati on, were investigated in C57BL/6 and DBA/2 mice using a one-trial inhi bitory avoidance task, drug treatment being given immediately after th e acquisition trial. Post-trial administration of oxotremorine facilit ated, while post-trial administration of 5-MeODMT inhibited memory ret ention of both strains in a dose-dependent fashion. The DBA/2 strain w as more affected by oxotremorine than the C57BL/6 mice; no strain-depe ndent sensitivity to serotonergic agonist administration was observed. In both strains, the combination of oxotremorine plus 5-MeODMT inhibi ted the performance improvement shown by the administration of the cho linergic agonist alone. The facilitatory role of cholinergic stimulati on on retention performance was confirmed and an inhibitory action of the serotonergic system on memory processes was suggested. Moreover, t he present results support a functional interaction between cholinergi c and serotonergic systems on memory consolidation.