INVOLVEMENT OF CHOLINERGIC SYSTEMS IN THE DEFICIT OF PLACE LEARNING IN MORRIS WATER MAZE TASK INDUCED BY BACLOFEN IN RATS

Effects of oxotremorine on the deficit of place learning in the Morris water maze task induced by baclofen and scopolamine were examined to determine the involvement of brain cholinergic systems in the deficit of learning induced by baclofen. Rats were given 4 training trials per day with the submerged platform at a fixed location in the maze for 4 days. On day 4, rats were required to swim in the pool without the pl atform after the 4th training trial (probe test). Baclofen as well as scopolamine dose-dependently increased the escape latency in the train ing trials. In the probe test, baclofen as well as scopolamine dose-de pendently reduced the duration in the quadrant where the platform had been originally located. Increased latency in the training trials and reduced duration in the probe test induced by scopolamine were dose-de pendently attenuated by oxotremorine. Increased latency and reduced du ration in the baclofen-treated rats were improved by oxotremorine as w ell as 2-hydroxysaclofen. Baclofen but not scopolamine induced motor i ncoordination in the rotarod test. Oxotremorine failed to improve moto r incoordination induced by baclofen. These results suggest that choli nergic systems may be involved in the deficit of place learning induce d by baclofen, and that the ameliorative effects of oxotremorine may n ot be due to improvement of motor incoordination.