Effects of acute and chronic maprotiline administration on inhibitory avoidance in male mice.

The effects of acute and chronic administration of maprotiline (5, 10 or 20 mg/kg, intraperitoneally) were assessed on inhibitory avoidance in male mice. Acute administration of maprotiline before training did not effect training phase latencies, but impaired performance (i.e. produced shorter latencies) in the test at doses of 5 and 20 mg/kg. When given after training, the drug did not modify test latencies at any of the doses used. Chronic administration for 21 days (interrupted 24 h before training) also shortened latencies in the test but not in training. An experiment on the acute effects of maprotiline on analgesia (determination of flinch and jump thresholds for increasing electric foot shock levels), at the doses stated, was carried out on naive animals. No analgesic effect of the drug was found. Taken together, the results indicate that acute maprotiline produces anterograde amnesia, and tolerance does not appear after 21 days of treatment.