SCOPOLAMINE-INDUCED AND MORPHINE-INDUCED DEFICITS IN WATER MAZE ALTERNATION - FAILURE TO ATTENUATE WITH GLUCOSE

Glucose has previously been shown to improve performance on memory tas ks and to ameliorate performance deficits induced by scopolamine or mo rphine. To test the generality of these observations. Sprague-Dawley r ats were trained to alternate choices to reach an escape platform in a two-choice circular water maze. The rats attained a high level of alt ernation, alternating on a mean of 9 of 10 daily trials. Daily glucose injections (100 and 250 mg/kg) failed to facilitate acquisition of th e alternation. Single injections of scopolamine (0.5, 1.0, and 2.0 mg/ kg), but not methylscopolamine (0.5 mg/kg), and daily injections of sc opolamine (0.5 mg/kg) or morphine (5.0 mg/kg) impaired alternation per formance. The scopolamine- and morphine-induced deficits in alternatio n behavior were not ameliorated by pretrial glucose injections at dose s which have previously been found to be effective (100 and 250 mg/kg) . The mechanism of glucose facilitation of memory is currently unknown . The present results show that glucose given at previously establishe d effective doses does not activate the mechanism or produces too weak an effect to be observed in water maze alternation. (C) 1996 Academic Press, Inc.