Pargyline conjugate-induced long-term activation of monoamine oxidase as an immunological model for depression

We describe an animal model of long-term depression based on active immuniz ation of albino rats against BSA-conjugated inhibitor of monoamine oxidase, antidepressant, pargyline. Immunization resulted in anti-pargyline antibod y formation and significant activation of monoamine oxidase A in brain. Imm unized rats demonstrated potent decrease of motor, orientation and explorat ory activity, increase of the immobility time ("despair") in Porsolt test, as well as notable signs of fear and anxiety in elevated plus maze. The cog nitive processes were not significantly affected: the speed of learning wit h negative and positive reinforcement was not diminished. Complex effect on craving for alcohol (long-term suppression after short-term increase) was also demonstrated. The long-term (more than 45 days) depression achieved in this model makes it potentially important tool for testing new antidepress ant pharmaceuticals.