Nonparallel changes in brain monoamines of pyridoxine-deficient growing rats.
The effects of a large number of neurotropic drugs have been attributed to changes in the metabolism of 5-hydroxytryptamine. The aromatic amino acid decarboxylase considered to decarboxylate both dihydroxyphenylalanine and 5-hydroxytryptophan requires pyridoxal phosphate as coenzyme. Thus, in pyridoxine deficiency one would expect a decrease of serotonin as well as the catecholamines of the brain. In the present study we have found a very significant decrease in brain serotonin of the pyridoxine-deficient growing rat. However, the brain levels of norepinephrine and dopamine were not altered. This decrease in serotonin does not result from a decrease either in the brain level of trytophan or the activity of tryptophan hydroxylase. Increased degradation of serotonin measured by the levels of its metabolite, 5-hydroxyindoleacetic acid is also excluded, thus suggesting the possibility that the decarboxylation of 5-hydroxytryptophan is decreased in pyridoxine deficiency.
D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D001933:Brain Stem / Q000187:drug effects / Q000201:enzymology; D004298:Dopamine / Q000378:metabolism; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D009929:Organ Size / Q000187:drug effects; D010293:Pargyline / Q000494:pharmacology; D011339:Probenecid / Q000494:pharmacology; D011736:Pyridoxine / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000378:metabolism*; D013997:Time Factors; D014364:Tryptophan / Q000097:blood / Q000378:metabolism; D014365:Tryptophan Hydroxylase / Q000378:metabolism; D026681:Vitamin B 6 Deficiency / Q000378:metabolism*
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D010293:Pargyline; D014365:Tryptophan Hydroxylase; D011736:Pyridoxine; D011339:Probenecid; D004298:Dopamine; D009638:Norepinephrine