MAO-B inhibitor deprenyl and beta-phenylethylamine potentiate [D-ALA2]-Met-enkephalinamide-induced seizures

The relationship between deprenyl (MAO-B inhibitor), beta-phenylethylamine (PEA, MAO-B substrate) and [D-Ala2]-Met-enkephalinamide (DALA)-induced seizure was studied in the urethane-anaesthetized rats. A combined electromyographic (EMG) and electrocorticographic (ECoG) method was used. PEA (20-100 micrograms ivt) or DALA (10 micrograms ivt) induced myoclonic contractions (MC) in the submandibular muscle and epileptiform pattern with spike activity in the ECoG. Administration of subconvulsant doses of PEA (5-10 micrograms ivt 0.5-1 min before DALA) significantly increased DALA-induced seizure activity. Similarly, blockade of MAO-B with deprenyl (3-48 mg/kg ip) also enhanced DALA-induced epileptiform pattern. It is evident from this study that MAO-B system significantly modulates the excitatory phenomena induced by DALA. These findings of interactions between MAO-B system and enkephalinergic one, might be of relevance in the clinical situations such as psychosis, stress, a use of tricyclic antidepressants and all other cases, where the alteration of MAO-B system is a part of disease or induced during drug therapy.