COMPARISON OF BEHAVIORAL-EFFECTS OF MOCLOBEMIDE AND DEPRENYL DURING FORCED SWIMMING

The present study compared the antiimmobility effects of 1-deprenyl (D EP) and moclobemide (MOC) to the classic antidepressant imipramine (IM I), using an ethological approach. To investigate the degree of MAO-B inhibition by DEP and MOC, combination of treatments of ineffective do ses of phenylethylamine (PHEA) with DEP or with MOC were administered in three doses before immobility was tested in the forced-swimming par adigm. Tests were videotape recorded for analysis of the frequency and duration of the behaviors during the procedure. There was a significa nt, dose-dependent decrease in immobility duration and an increase in mobility duration of rats treated with IMI. Both active behaviors of c limbing and swimming were equally enhanced by the tricyclic antidepres sant, climbing behavior composing 75% of the mobile behaviors. The int ermediate doses of the MAOIs tested, DEP 0.25 mg/kg and MOC 30 mg/kg, decreased immobility and increased mobility. The antiimmobility effect of DEP was due to longer climbing behavior while MOC enhanced swimmin g duration. No behavioral changes were seen with the administration of the lower and higher doses of the MAOI. Potentiation of the antiimmob ility effects was observed when ineffective doses of PHEA and of DEP o r MOC were administered in combination. Differences between the MAO in hibitors on the active behaviors were also observed when administered with PHEA; DEP and PHEA significantly increased climbing and MOC and P HEA increased swimming. This preclinical evaluation of selective MAO i nhibitors indicates that both MAO-A and MAO-B inhibitors have antidepr essant effects. However, to clearly demonstrate that these antiimmobil ity effects are a consequence of increased brain concentrations of any one of the several monoamines implicated in the mechanism of action o f DEP or MOC should be the subject of future studies. (C) 1998 Elsevie r Science Inc.