Acute effects of maprotiline on learning, anxiety, activity and analgesia in male and female mice.

The acute effects of maprotiline (2.5, 5, 10, 15, 20 or 25 mg/kg) on learning, anxiety, activity and analgesia in male and female mice were evaluated. In addition to inhibitory avoidance learning, anxiety and locomotor activity were measured in the same animals using an elevated plus-maze. A study of the acute effects of maprotiline (15, 20 or 25 mg/kg) on analgesia was carried out in naive animals of both sexes. Maprotiline impaired inhibitory avoidance at doses of 15, 20 or 25 mg/kg. The highest dose produced an anxiolytic effect in females, and the doses of 20 and 25 mg/kg reduced locomotor activity. Analgesia was observed with the highest dose. The impairment of inhibitory avoidance by maprotiline would seem to be independent of the drug's influence on anxiety, is not shadowed by an instrumental performance deficit and, at least in the case of the highest dose, could be influenced by the drug's effects on analgesia. It is hypothesized that acquisition is the memory process principally affected by maprotiline, and in particular stimuli processing. The lack of sex differences in the effects of maprotiline on inhibitory avoidance supports the generalization of findings previously obtained only in males.