Guanosine impairs inhibitory avoidance performance in rats

The nucleoside guanosine, previously found to exert trophic and neuroprotective effects, was found to impair retention of inhibitory avoidance responses, with a complete effect at 7.5 mg/kg i.p, pretraining. Treated animals, when retrained week later, showed normal learning ability. Guanosine injected immediately after training or pretest did not alter retention latency. Combined pretraining and pretest treatments with guanosine failed to reverse its amnestic effect. excluding the contribution of state dependency. Open field parameters and shock sensitivity were mostly unaltered by guanosine. These results suggest an amnestic effect of guanosine on inhibitory avoidance in rats, in a pattern compatible with inhibition of glutamatergic activity. However, the mechanism for the amnestic effect of guanosine is yet to be elucidated. NeuroReport 11:2537-2540 (C) 2000 Lippincott Williams & Wilkins.