The behavioural effects of phenelzine and phenylethylamine may be due to amine release

Intraperitoneal administration of phenelzine (PLZ) or of beta-phenylethylamine (PE) quickly leads to short periods of behavioural activation, which are primarily dopaminergic and serotonergic in nature, respectively. In order to determine whether these behavioural effects are due to PLZ- or PE-induced displacement of dopamine (DA) or serotonin (5HT), the ability of these compounds to stimulate release of radiolabelled DA and 5HT from slices of rat striatum was assessed. Additionally, at various times following IP administration of behaviourally active doses of PLZ or PE to rats, the striatal levels of the drugs were measured. Both PLZ and PE were able to stimulate a greater release of radiolabelled DA than of 5HT. Lower concentrations of PE (0.8, 8.0 microM) than of PLZ (100 microM, 1 mM) stimulated release. The striatal levels (approximately 200 microM) of PLZ, as well as of PE, attained at times corresponding to behavioural activation seemed sufficient to cause release of both DA and 5HT. It was concluded, therefore, that the mode of action of these compounds may involve displacement, or release, of these biogenic amines, though it is not clear how such release ultimately leads to the behaviours observed.