Role of monoamines in behavior of reserpinized rats given tranylcypromine stereoisomers.

The effects of tranylcypromine stereoisomers [(+)-TCP and (-)-TCP] on behavior were studied in reserpinized rats. Rats given reserpine showed a behavioral syndrome characterized by hypoactivity. Administration of (+)-TCP to reserpinized rats led to a dose-dependent increase in their locomotor activity. At a dose of 15 mg/kg, (+)-TCP produced activation, stereotypy and hyperstimulation in reserpinized rats. In contrast, (-)-TCP failed to influenced the behavior of reserpinized rats reliably. Pharmacological studies using agonists and antagonists of monoaminergic functions showed the actions of (+)-TCP to depend on presynaptic serotonergic and catecholaminergic functions. The results provide another example of stereoselective effects of tranylcypromine stereoisomers on behavior mediated mainly by monoaminergic neurotransmission.