Neurobiology of Pyridoxine

Abstract

Pyridoxal 5'-phosphate (PLP) is the major coenzymatic form of pyridoxine. There are over one hundred known pyridoxal 5'-phosphate-dependent reactions, most of which are involved in the metabolism of various amino acids . Pyridoxamine 5'-phosphate can function in aminotransf erase reactions by the cyclic regeneration of the two active phosphate forms. Pyridoxal 5'-phosphate-dependent reactions studied in the nervous system are involved in the catabolism of various amino acids.The putative neurotransmitters , dopamine, norepinephrine , serotonin , histamine , aminobutyric acid and taurine , as well as the sphingoiipids and poly amines are synthesized by PLP-dependent enzymes. Of these enzymes, three ( glutamic acid decarboxylase , 5-hydroxytryptophan decarboxylase and crnithine decarboxylase) seem to have crucial roles (Fig. '). The clinical effects of pyridoxine deficiency can be explained on the basis of the known decreases in the activities of these enzymes (1). EXPERIMENTAL PYRIDOXINE DEFICIENCY IN THE NEONATE RATDakshinamurti and Stephens ( 2) first reported the production of congenital pyridoxine deficiency .Our observations extended the "chronic fetal distress" hypothesis of Gruenwald ( 3) to include effects on the development of the central nervous system. We later showed that a deficiency of pyridoxine in rat pups could be produced by depriving the dam of dietary pyridoxine during lactation (4). Such a deficiency has been characterized using biochemical and electrophysiological parameters. The electroencephalogram (EEG)

Environmental Effects on Compulsive Tail Chasing in Dogs

“…All types of DNA and RNA syntheses are dependent on B6. In the brain, PLP-dependent enzymes are involved in the metabolism of many amino acid and amine neurotransmitters such as dopamine, serotonin, glutamate, glycine, GABA, D-serine and taurine [48]. They are also important in the synthesis of neuroprotective compounds such as kynurenic acid.…”

Pyridoxine Enhances Cell Proliferation and Neuroblast Differentiation by Upregulating the GABAergic System in the Mouse Dentate Gyrus

“…In particular, pyridoxine and its active form PLP have been reported to promote neuronal survival and improve cognitive functions like memory [9,10]. In addition, many neurotransmitters such as dopamine, norepinephrine, GABA, serotonin and taurine are synthesized by PLP-dependent enzymes [11]. Pyridoxine deficiency leads to a reduction of GABA concentration in the whole brain and people with this deficiency exhibit a range of neurological symptoms, including tremors and seizures [12].…”

Folate nutrition is related to neuropsychological functions in the elderly

“…Thiamin and riboflavin coenzymes, thiamin pyrophosphate and flavin adenine dinucleotide and flavin mononucleotide namely, are involved in the mitochondrial energy metabolism in neurons (Baker & Tarnopolsky, 2003; Sheu et al, 1998). Vitamin B 6 coenzyme, pyridoxal-5-phosphate is important for the metabolism of amino acids and proteins, neurotransmitters, and sphingolipids in the central nervous system (Dakshinamurti et al, 1985). Folate is required in the synthesis of S-adenosylmethionine (SAMe), a methyl donor for many important brain biomolecules such as phospholipids, guanidoacetate, neurotransmitters, amino acids, and nucleic acids (Bottiglieri et al, 2000; Hirata & Axelrod, 1980; Wagner, 1995).…”