Milacemide treatment in mice enhances acquisition of a Morris-type water maze task

Abstract

The N-methyl-D-aspartate (NMDA) subtype of the glutamate receptor appears to be involved with processes of learning and memory. A neutral amino acid binding site is known to exist on the NMDA complex. Glycine binds with high affinity to this site and has been found to potentiate NMDA activity. 2-N-Pentylaminoacetamide HCl (milacemide) is a glycine agonist that has been found to enhance performance of rodents in passive and active avoidance tasks and has improved the performance of humans in several word retrieval tasks. We evaluated the effects of milacemide on the performance of male C57BL/6J mice in a complex spatial task, the Morris water maze. Because NMDA receptor activation appears involved in induction of long-term potentiation, it was hypothesized that milacemide administration would be involved in task acquisition. Therefore, mice were treated with either milacemide (10 mg/kg) or vehicle 1 h prior to training on each of 4 consecutive days. Results indicated that mice treated with milacemide learned the task significantly faster than controls over 4 days of training, as measured by mean distance (cm) to reach the goal platform. Therefore, agonism of the glycine site on the NMDA receptor appears to facilitate performance of learning in a spatial memory task.