Phospholipid liposomes potentiate the inhibitory effect of antidepressant drugs on immobility of rats in a despair test (constrained swim).

Male rats forced to swim in a cylinder assumed an immobile posture. Immobility was reduced by antidepressant drugs, such as imipramine, desimipramine, iproniazid and mianserin injected 24, 5 and again 1 h prior to behavioral testing. Subchronic (4, 7 and 10 days) treatment with sonicated preparations of bovine hypothalamic phospholipid liposomes potentiated the inhibitory effect of all antidepressant drugs in the despair test. Acute administration of phospholipid liposomes failed to influence the drug effect. Furthermore, neither subchronic nor acute administration of phospholipid liposomes per se modified the immobility in the despair test. It is possible that the action of phospholipid liposomes on the inhibitory effect of antidepressant drugs on immobility of rats in the despair test may depend on potentiation of antidepressant-induced change in the sensitivity of monoamine receptors in the brain.