EFFECT OF INTRAVENTRICULAR-INJECTIONS OF DIHYDRO-BETA-ERYTHROIDINE (DH-BETA-E) ON SPATIAL MEMORY IN THE RAT

The analysis of the behavioral effect of the nicotinic acetylcholine r eceptor (nAChR) antagonists has been generally based on drugs which ac t at the associated ion channel. In contrast dihydro-beta-erythroidine (DH beta E) is a competitive antagonist at the nAChR. Using rats, DH beta E was injected intraventricularly prior to training in two spatia l tests, the Morris Water Maze and a Win-Stay radial maze. In addition DH beta E 300 nmol was used to reverse the effect of (-)-nicotine on locomotor activity. In the Morris Water Maze DH beta E (300 nmol) disr upted memory of the platform location as measured by crosses of the ar ea in a probe trial. At 300 nmol DH beta E showed no sensorimotor effe cts in a visible platform test. In the Win-Stay task there was a signi ficant, dose dependent disruption of spatial memory. A dissociation of nicotine's effects on locomotor activity was observed, in that DH bet a E 300 nmol was able to significantly attenuate (-)-nicotine enhancem ent of horizontal motor activity, but did not affect the initial reduc tion of vertical activity. Nicotinic processing of memory appears to b e involved in these tests of spatial memory.