Age effects on monoamine turnover of the rat substantia nigra.
Measurement of turnover of dopamine (DA), noradrenaline (NA) and serotonin (5-hydroxytryptamine (5-HT), and their metabolites has been performed in 6- and 24-month-old rats. Dopamine synthesis in 24-month-old rats did not show any change with respect to 6-month-old rats. However, our results seem to indicate decreased DA release in 24-month-old rats. This hypothesis could be supported by the changes found in the 3-methoxytyramine (3-MT) accumulation rate after monoamine oxidase inhibition with pargyline. The turnover of NA and its main metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG) decreased in 24-month-old rats compared with 6-month-old rats. Serotonin synthesis did not change in 24-month-old rats with respect to 6-month-old rats. However, the metabolism of 5-HT quantified as turnover of 5-hydroxy-3-indoleacetic acid (5-HIAA) increased in 24-month-old rats with respect to 6-month-old rats. The monoamine oxidase B:monoamine oxidase-A ratio increased in 24-month-old rats. The significance of these changes is discussed.
Venero
J L
JL
Departamento de Bioquímica, Universidad de Sevilla, Spain.
Machado
A
A
Cano
J
J
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D006916:5-Hydroxytryptophan / Q000378:metabolism; D000375:Aging / Q000502:physiology*; D000818:Animals; D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D015306:Biogenic Monoamines / Q000378:metabolism*; D004298:Dopamine / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000378:metabolism; D006719:Homovanillic Acid / Q000378:metabolism; D006834:Hydrazines / Q000494:pharmacology; D066298:In Vitro Techniques; D007980:Levodopa / Q000378:metabolism; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000378:metabolism; D009638:Norepinephrine / Q000096:biosynthesis / Q000378:metabolism; D010293:Pargyline / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism; D013378:Substantia Nigra / Q000254:growth & development* / Q000378:metabolism
D065105:Aromatic Amino Acid Decarboxylase Inhibitors; D015306:Biogenic Monoamines; D006834:Hydrazines; D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D007980:Levodopa; D008734:Methoxyhydroxyphenylglycol; D010293:Pargyline; C004297:3-hydroxybenzylhydrazine; D006916:5-Hydroxytryptophan; C001746:3-methoxytyramine; D004298:Dopamine; D009638:Norepinephrine; D006719:Homovanillic Acid