Interactions between angiotensin II and baclofen in shuttle-box and passive avoidance performance

Abstract

In experiments on male rats, we established that angiotensin-II (AT II) at a dose of 0.1 μg injected intracerebroventricularly immediately after training improved memory when retention tests (active and passive avoidance) were given 24 hours later. Baclofen at doses of 2,5 and 10 mg/kg injected intraperitoneally immediately after training also improved retention in both active and passive avoidance tasks. Baclofen at a dose of 20 mg/kg was without effect on active avoidance performance. Combination of AT II and baclofen (2,5 and 10 mg/kg) facilitated memory in active avoidance as compared to controls, but impaired retention as compared to the AT II-treated group. The impairment of the AT II-improved retention was stronger when the dose of baclofen in the combination was 20 ng/kg. Combination of AT II and baclofen (10 mg/kg) did not impair retention in passive avoidance. These data favor the view that GABA receptors may interfere with the AT II effects on memory consolidation or retention and that interactions of GABA (GABA A and GABA B) receptors with AT II receptors are of importance for memory processes.