title: Modification of dopamine and norepinephrine metabolism in the rat brain by monoamine oxidase inhibitors.
abstract: The treatment of Sprague-Dawley rats with monoamine oxidase (MAO) inhibitors (pargyline, tranylcypromine) profoundly affects dopamine (DA) and norepinephrine (NE) metabolism in the brain. In these rats injection of L-dopa led to large increases in norepinephrine (NE), normetanephrine (NMN) and 3-methoxytyramine (3-MT) in brain tissues. The response of MAO-inhibited rats to L-dopa contrasted sharply with those not treated with the MAO inhibitor; the latter showed no change in NE, NMN and 3-MT after similar administration of L-dopa. The increase of NE in pargyline-treated rats correlated closely with that of DA in the hypothalamus and in the brain stem. This response was greatly diminished in rats previously treated with the neurotoxin 6-hydroxydopamine, but was restored when the treatment with 6-hydroxydopamine was accompanied by desimipramine. This suggests that noradrenergic neurons were the origin of the NE response. The NMN and 3-MT increases occurring only in the rats treated with a MAO inhibitor were highly correlated. The results suggested that MAO inhibitor may affect entry of DA into catecholaminergic storage where NE synthesis takes place and from where DA is released.
authors: Laboratory of the Autonomic Nervous System, University of Montreal, Quebec, Canada.
authors: N T
authors: NT
authors: Buu
authors: M
authors: M
authors: Angers
authors: J
authors: J
authors: Duhaime
authors: O
authors: O
authors: Kuchel
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D004298:Dopamine / Q000031:analogs & derivatives / Q000378:metabolism*; D007980:Levodopa / Q000494:pharmacology; D008297:Male; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism*; D009647:Normetanephrine / Q000378:metabolism; D010293:Pargyline / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
chemical_list: D008996:Monoamine Oxidase Inhibitors; D009647:Normetanephrine; D007980:Levodopa; D010293:Pargyline; C001746:3-methoxytyramine; D004298:Dopamine; D009638:Norepinephrine