VITAMIN B6 AND CLINICAL STUDIES USING IT WITH 5-HTP

Clinical studies indicate that it is better to take 5-HTP with vitamin B6 because B6 may increase production of serotonin in the brain. In animal clinical studies with rats and monkeys, the presence of spare amounts of B6 increased production of serotonin in the brain from 5-HTP by up to 60%. In recent clinical studies, vitamins B6 have been shown to play a role in tryptophan metabolism, which helps convert 5 HTP to serotonin more efficiently.

Neural Transm Gen Sect. 1995;102(2):91-7.

Pyridoxine effect on synthesis rate of serotonin in the monkey brain measured with positron emission tomography.

Hartvig P, Lindner KJ, Bjurling P, Laengstrom B, Tedroff J.

Uppsala University PET Centre, Uppsala, Sweden.

The influence of the co-factor pyridoxine, vitamin B6, on the activity of aromatic amino acid decarboxylase enzyme was studied by positron emission tomography, PET in the brain of the Rhesus monkey using the precursor for serotonin synthesis 5-hydroxy-L-tryptophan (5-HTP) radiolabelled with 11C in the beta-position. The rate constant for the formation of serotonin in the corpus striatum was calculated using a two tissue compartment model with reference area in the brain. In baseline investigations, the mean rate constants (+/-S.D:) for selective utilization of [11C]5-HTP to form [11C]serotonin in the corpus striatum was 0.0080 +/- 0.0011 min(-1). Pretreatment with intravenous pyridoxine hydrochloride 10 mg/kg bodyweight before doing a second PET study resulted in an enhanced rate constant by a mean of 20%. The rate increase was statistically significant. The increase varied considerably in different monkeys from no effect to more than 60%. The effect of pyridoxine on aromatic amino acid decarboxylase activity supported a regulatory role of pyridoxine on the synthesis of neurotransmitter in vivo, and may be of importance in diseases with deficiencies in neurotransmitter function.

PMID: 8748674 [PubMed - indexed for MEDLINE]

Klin Wochenschr. 1990 Jan 19;68(2):142-5.

Influence of B vitamins on binding properties of serotonin receptors in the CNS of rats.

Dakshinamurti K, Sharma SK, Bonke D.

Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.

Treatment of normal adult rats with pyridoxine or a B-vitamin mixture resembling Neurobion led to an increase in serotonin content of various brain areas and to a decrease in the number of serotonin S2 receptors. The results indicate that the pyridoxal phosphate level in regions of the brain regulates the extent of decarboxylation of 5-hydroxytryptophan, the precursor of serotonin. The results also suggest a continuum from deficiency in pyridoxine to treatment of animals with a moderate excess of pyridoxine which is reflected in the synthesis and secretion into the synaptic cleft of the neurotransmitter serotonin.

PMID: 2157087 [PubMed - indexed for MEDLINE]