Dietary pyridoxine interaction with tryptophan or histidine on brain serotonin and histamine metabolism.
We studied the metabolic effects of high dietary intakes of pyridoxine and of the substrate-cofactor interaction between dietary histidine or tryptophan and pyridoxine in rat brain. In the substrate-cofactor interaction study, histamine and serotonin levels were determined in rats fed elevated or requirement levels of substrate (histidine: 0.3% and 0.8%, tryptophan: 0.15% and 0.6%) and excess or requirement levels of pyridoxine HCl (7 mg vs. 3,000 mg/kg). Excess pyridoxine intake caused a differential effect on brain histamine concentration--inhibitory with the requirement level of histidine (-29%), and stimulatory (+21%) with the elevated level of histidine. When dietary tryptophan was fed at the requirement level, excess pyridoxine caused essentially no changes in hypothalamic serotonin and 5HIAA (-2%, -2%). With elevated tryptophan intake, excess pyridoxine significantly increased serotonin and 5HIAA (+32%, +20%) in the hypothalamus. These results indicate a clear interaction between substrate and coenzyme precursor which influences brain metabolism of histamine and serotonin.
Lee
N S
NS
Department of Nutrition, State University of New Jersey, New Brunswick 08903.
Muhs
G
G
Wagner
G C
GC
Reynolds
R D
RD
Fisher
H
H
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D004032:Diet; D004347:Drug Interactions; D006632:Histamine / Q000378:metabolism; D006639:Histidine / Q000494:pharmacology*; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D011732:Pyridoxal Phosphate / Q000378:metabolism; D011736:Pyridoxine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism; D014364:Tryptophan / Q000494:pharmacology*
D012701:Serotonin; D006639:Histidine; D011732:Pyridoxal Phosphate; D006632:Histamine; D014364:Tryptophan; D011736:Pyridoxine