(-)-Deprenyl a selective MAO "B' inhibitor, increases [3H]imipramine binding and decreases beta-adrenergic receptor function

In rats, a selective inhibition for 3 weeks of monoamineoxydase (MAO) type B elicited by daily doses of pargyline (2.5 mumol/kg) or (-)-deprenyl (1 mumol/kg) attenuated the NE dependent stimulation of cortical adenylate cyclase and reduced the number of brain recognition sites for beta-adrenergic receptor ligands. Similar actions were not elicited by a comparable dose regimen of (+)-amphetamine. Hence the inhibition of MAO B mimicks responses that are typically elicited by antidepressants. The molecular nature of the mechanisms involved cannot be understood, however, these mechanisms may not be identical for pargyline and (-)-deprenyl because this drug but not pargyline increased the number of [3H]imipramine recognition sites. Even high daily doses of pargyline (100 mumol/kg, for 3 weeks) failed to change [3H]imipramine binding though they still down regulated beta-adrenergic recognition sites, the NE stimulation of adenylate cyclase and the Bmax of [3H]mianserin and [3H]spiroperidol binding.