title: Folate deficiency and homocysteine induce toxicity in cultured dorsal root ganglion neurons via cytosolic calcium accumulation.
abstract: Folate deficiency induces neurotoxicity by multiple routes, including increasing cytosolic calcium and oxidative stress via increasing levels of the neurotoxin homocysteine (HC), and inducing mitochondrial and DNA damage. Because some of these neurotoxic effects overlap with those observed in motor neuron disease, we examined the impact of folate deprivation on dorsal root ganglion (DRG) neurons in culture. Folate deprivation for 2 h increased cytosolic calcium and reactive oxygen species (ROS) and impaired mitochondrial function. Treatment with nimodipine [an L voltage-sensitive calcium channel (LVSCC) antagonist], MK-801 (an NMDA channel antagonist) and thapsigarin (an inhibitor of efflux of calcium from internal stores) indicated that folate deprivation initially induced calcium influx via the LVSCC, with subsequent additional calcium derived from NMDA channels and internal stores. These compounds also reduced ROS and mitochondrial degeneration, indicating that calcium influx contributed to these phenomena. Calcium influx was prevented by co-treatment with 3-deaza-adenosine, which inhibits HC formation, indicating that HC mediated increased cytosolic calcium following folate deprivation. Nimodipine, MK-801 and thapsigargin had similar effects following direct treatment with HC as they did following folate deprivation. These findings support the idea that folate deprivation and HC treatment can compromise the health of DRG neurons by perturbing calcium homeostasis.
authors.affiliation: Center for Cellular Neurobiology and Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA 01854, USA.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Tjiattas
authors.forename: Daniela O
authors.initials: DO
authors.lastname: Ortiz
authors.forename: Sirikarnt
authors.initials: S
authors.lastname: Dhivant
authors.forename: Kerrie
authors.initials: K
authors.lastname: Mitton
authors.forename: Eugene
authors.initials: E
authors.lastname: Rogers
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Shea
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000814:Aniline Compounds / Q000032:analysis; D000818:Animals; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D002478:Cells, Cultured; D002642:Chick Embryo; D003600:Cytosol / Q000378:metabolism; D016291:Dizocilpine Maleate / Q000494:pharmacology; D005492:Folic Acid / Q000502:physiology*; D005494:Folic Acid Deficiency / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006710:Homocysteine / Q000633:toxicity*; D008564:Membrane Potentials / Q000187:drug effects; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009553:Nimodipine / Q000494:pharmacology; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000032:analysis / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D014966:Xanthenes / Q000032:analysis
chemical_list: D000814:Aniline Compounds; D017382:Reactive Oxygen Species; D014966:Xanthenes; D006710:Homocysteine; C059715:Fluo-3; D009553:Nimodipine; D019284:Thapsigargin; C055133:3-deazaadenine; D016291:Dizocilpine Maleate; D005492:Folic Acid; D000225:Adenine; D002118:Calcium