Behavioural effects of pinoline in the rat forced swimming, open field and elevated plus-maze tests

Pinoline (6-methoxy-1,2,3,4-tetrahydro-beta-carboline) is a naturally occurring compound in the mammalian body which inhibits serotonin (5-hydroxytryptamine) uptake and monoamine oxidase-A activity. The present study was designed to assess potential antidepressant- or anxiolytic-like behavioural effects of pinoline in rat forced swimming, open field and elevated plus-maze tests. In the forced swimming test pinoline dose-dependently reduced the immobility time, starting from a dose of 8 mg kg-1. In the open field test pinoline reduced the total open field activity. This effect was significant at 20 mg kg-1, whereas the dose of 15 mg kg-1 only significantly reduced the number of rearings. In the plus-maze test pinoline decreased the total number of arm entries, the number of line crossings and time spent in the open part of the apparatus, but increased the number of approaches to the open part of the maze. The effects of pinoline were dose-dependent in all three behavioural tests used. Since antidepressant drugs reduce the immobility time in the forced swimming test but typically inhibit activity in open field and elevated plus-maze tests, the behavioural effects of pinoline resemble those of drugs with an antidepressant profile.