Dorsal hippocampal muscarinic acetylcholine and NMDA receptors disrupt water maze navigation.

The present study investigated the effects of bilateral dorsal hippocampal infusions with muscarinic acetylcholine (scopolamine; 3 and 10 micrograms per hemisphere) and N-methyl-D-aspartate (NMDA) (CPP; 0.01 and 0.03 microgram per hemisphere) antagonists on acquisition (drug delivered before daily training), consolidation (drug delivered after daily training) and retrieval (drug delivered only before spatial bias test) performance in a water maze (WM) spatial navigation test. Scopolamine 10 micrograms disrupted acquisition, but had no effect on consolidation or retrieval. CPP 0.03 microgram disrupted acquisition and retrieval behaviour. A combination of subthreshold doses of CPP (0.01 microgram) and scopolamine (3 micrograms) disrupted acquisition performance. The treatments did not disrupt navigation to a clearly visible escape platform. The present data indicate that dorsal hippocampal NMDA and muscarinic acetylcholine receptors are important for spatial navigation behaviour.