SUBCHRONIC-MK-801 TREATMENT TO JUVENILE RATS ATTENUATES ENVIRONMENTAL-EFFECTS ON ADULT SPATIAL-LEARNING

Treatment with the non-competitive NMDA receptor blocker MK-801 (0.16 mg/kg), given to juvenile rats before and after the exposure to an enr iched environment on alternate days for 4 weeks, attenuated the improv ements in spatial learning and open field adaptation which resulted fr om such environmental stimulation. Drug treatment affected the consoli dation of experiences as an injection given after exposure to the enri ched environment was needed to demonstrate this effect. In addition, M K-801 administration diminished the adverse effect of stimulus depriva tion-the slow learning rate normally seen in rats housed in impoverish ed environment. Radioligand binding studies showed that drug treatment decreased [H-3]MK-801 binding sites in cortex. The learning, activity and receptor binding effects were measured 4 months from cessation of the drug treatment and environmental manipulation. The results suppor t the role of NMDA receptors in mediating cognitive changes associated with environmental stimulation.