Dopamine metabolism in the guinea pig striatum: role of monoamine oxidase A and B.
These studies were carried out to determine whether the greater abundance of monoamine oxidase B in the guinea pig affects the actions of (-)-deprenyl on dopamine metabolism in whole tissue or in extracellular fluid. The administration of (-)-deprenyl in doses that do not affect monoamine oxidase A activity (1-4 mg kg-1, 2 h) increases striatal 2-phenylethylamine and dopamine concentrations and reduces 3,4-dihydroxyphenylacetic acid. No effects were observed on striatal homovanillic acid, 5-HT and 5-hydroxyindole acetic acid. Inhibition of monoamine oxidase A with clorgyline with doses up to 8 mg kg-1 (2 h) does not affect striatal 2-phenylethylamine but increases dopamine and 5-HT concentrations and reduces 3,4-dihydroxyphenyl-acetic acid and 5-hydroxyindole acetic acid. (-)-Deprenyl (2-4 mg kg-1) did not change the extracellular concentrations of dopamine but the higher dose produced a limited reduction in extracellular 3,4-dihydroxyphenylacetic acid. Inhibition of monoamine oxidase A and monoamine oxidase B with pargyline (75 mg kg-1, 2 h) significantly increased the levels of extracellular dopamine and reduced those of their acid metabolites. These results show that in the guinea pig striatum inhibition of monoamine oxidase B by (-)-deprenyl impairs the metabolism of dopamine in the whole tissue but does not produce a marked increase in extracellular dopamine.
Neuropsychiatric Research Unit, University of Saskatchewan, Saskatoon, Canada.
A V
AV
Juorio
I A
IA
Paterson
M Y
MY
Zhu
D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis; D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D006168:Guinea Pigs; D006719:Homovanillic Acid / Q000032:analysis; D008297:Male; D008995:Monoamine Oxidase / Q000502:physiology*; D010293:Pargyline / Q000494:pharmacology; D012642:Selegiline / Q000494:pharmacology
D015102:3,4-Dihydroxyphenylacetic Acid; D012642:Selegiline; D010293:Pargyline; D008995:Monoamine Oxidase; D004298:Dopamine; D006719:Homovanillic Acid