Glutamate transporter splice variant expression in an enriched pyramidal cell population in schizophrenia

Transl Psychiatry. 2015 Jun 9;5(6):e579. doi: 10.1038/tp.2015.74.

Abstract

Dysregulation of the glutamate transporters EAAT1 and EAAT2 and their isoforms have been implicated in schizophrenia. EAAT1 and EAAT2 expression has been studied in different brain regions but the prevalence of astrocytic glutamate transporter expression masks the more subtle changes in excitatory amino acid transporters (EAATs) isoforms in neurons in the cortex. Using laser capture microdissection, pyramidal neurons were cut from the anterior cingulate cortex of postmortem schizophrenia (n = 20) and control (n = 20) subjects. The messenger RNA (mRNA) levels of EAAT1, EAAT2 and the splice variants EAAT1 exon9skipping, EAAT2 exon9skipping and EAAT2b were analyzed by real time PCR (RT-PCR) in an enriched population of neurons. Region-level expression of these transcripts was measured in postmortem schizophrenia (n = 25) and controls (n = 25). The relationship between selected EAAT polymorphisms and EAAT splice variant expression was also explored. Anterior cingulate cortex pyramidal cell expression of EAAT2b mRNA was increased (P < 0.001; 67%) in schizophrenia subjects compared with controls. There was no significant change in other EAAT variants. EAAT2 exon9skipping mRNA was increased (P < 0.05; 38%) at region level in the anterior cingulate cortex with no significant change in other EAAT variants at region level. EAAT2 single-nucleotide polymorphisms were significantly associated with changes in EAAT2 isoform expression. Haloperidol decanoate-treated animals, acting as controls for possible antipsychotic effects, did not have significantly altered neuronal EAAT2b mRNA levels. The novel finding that EAAT2b levels are increased in populations of anterior cingulate cortex pyramidal cells further demonstrates a role for neuronal glutamate transporter splice variant expression in schizophrenia.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Animals
  • Antipsychotic Agents / pharmacology
  • Brain / drug effects
  • Brain / metabolism
  • Case-Control Studies
  • Excitatory Amino Acid Transporter 1 / genetics*
  • Excitatory Amino Acid Transporter 1 / metabolism
  • Excitatory Amino Acid Transporter 2 / drug effects
  • Excitatory Amino Acid Transporter 2 / genetics
  • Excitatory Amino Acid Transporter 2 / metabolism
  • Female
  • Glutamate Plasma Membrane Transport Proteins / genetics*
  • Glutamate Plasma Membrane Transport Proteins / metabolism
  • Gyrus Cinguli / drug effects
  • Gyrus Cinguli / metabolism*
  • Haloperidol / pharmacology
  • Humans
  • Male
  • Middle Aged
  • Polymorphism, Single Nucleotide
  • Protein Isoforms / genetics*
  • Protein Isoforms / metabolism
  • Pyramidal Cells / drug effects
  • Pyramidal Cells / metabolism*
  • RNA, Messenger / metabolism*
  • Rats
  • Real-Time Polymerase Chain Reaction
  • Schizophrenia / genetics*
  • Schizophrenia / metabolism

Substances

  • Antipsychotic Agents
  • Excitatory Amino Acid Transporter 1
  • Excitatory Amino Acid Transporter 2
  • Glutamate Plasma Membrane Transport Proteins
  • Protein Isoforms
  • RNA, Messenger
  • SLC1A2 protein, human
  • SLC1A3 protein, human
  • Slc1a2 protein, rat
  • Haloperidol