Nonparallel changes in brain monoamines of pyridoxine-deficient growing rats

Exp Brain Res. 1976 Nov 23;26(4):355-66. doi: 10.1007/BF00234219.


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.

MeSH terms

  • Animals
  • Animals, Newborn
  • Body Weight / drug effects
  • Brain / drug effects
  • Brain / growth & development
  • Brain / metabolism
  • Brain Stem / drug effects
  • Brain Stem / enzymology
  • Dopamine / metabolism
  • Hydroxyindoleacetic Acid / metabolism
  • Norepinephrine / metabolism
  • Organ Size / drug effects
  • Pargyline / pharmacology
  • Probenecid / pharmacology
  • Pyridoxine / pharmacology
  • Rats
  • Serotonin / metabolism*
  • Time Factors
  • Tryptophan / blood
  • Tryptophan / metabolism
  • Tryptophan Hydroxylase / metabolism
  • Vitamin B 6 Deficiency / metabolism*


  • Serotonin
  • Hydroxyindoleacetic Acid
  • Tryptophan
  • Pargyline
  • Tryptophan Hydroxylase
  • Pyridoxine
  • Probenecid
  • Dopamine
  • Norepinephrine