Estradiol alters only GAD67 mRNA levels in ischemic rat brain with no consequent effects on GABA

Hung Dong Joh, Robin V. Searles, Michael Selmanoff, Nabil Alkayed, Raymond C. Koehler, Patricia D. Hurn, Stephanie J. Murphy

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The present study tested the hypothesis that estradiol reduces tissue infarction after middle cerebral artery occlusion (MCAO) in estradiol-deficient females by augmenting glutamic acid decarboxylase (GAD) expression and thus activity, leading to increases in γ-amino-butyric acid (GABA) tissue levels. Glutamic acid decarboxylase is the principal enzyme for GABA synthesis and has two isoforms, GAD65 and GAD67, which differ in size and cellular distribution. Rats were ovariectomized 7 to 8 days before receiving no hormone, placebo, or 25 μg estradiol via subcutaneous implant 7 to 10 days before harvesting tissue in either ischemic cohorts after 2 h of MCAO (end-ischemia) or in nonischemic cohorts. Selected cortical and striatal regions were microdissected from harvested brains. GAD65/67 mRNA levels were determined by microlysate ribonuclease protection assay. End-ischemic GABA concentrations were determined by HPLC. Steroid treatment selectively decreased ischemic cortical GAD67 mRNA levels. In most brain regions evaluated, regional GABA concentrations increased with ischemia regardless of treatment. Estradiol blocked MCAO-induced increases in GABA concentration only in dorsomedial cortex. These data suggest that estradiol repletion in ischemic rat brain selectively decreases GAD67 mRNA levels but does not alter steady-state GABA concentrations. It may be that estradiol under ischemic conditions is attenuating GABA metabolism rather than enhancing synthesis or is augmenting other aspects of GABAergic transmission such as GABA transporters and receptors.

Original languageEnglish (US)
Pages (from-to)518-526
Number of pages9
JournalJournal of Cerebral Blood Flow and Metabolism
Volume26
Issue number4
DOIs
StatePublished - Apr 2006

Fingerprint

gamma-Aminobutyric Acid
Estradiol
Messenger RNA
Brain
Middle Cerebral Artery Infarction
Glutamate Decarboxylase
Ischemia
Tissue and Organ Harvesting
GABA Plasma Membrane Transport Proteins
Corpus Striatum
GABA Receptors
Butyric Acid
Ribonucleases
Infarction
Protein Isoforms
Steroids
High Pressure Liquid Chromatography
Placebos
Hormones
Enzymes

Keywords

  • Estradiol
  • Estrogen
  • GABA
  • GAD mRNA
  • Stroke

ASJC Scopus subject areas

  • Endocrinology
  • Neuroscience(all)
  • Endocrinology, Diabetes and Metabolism

Cite this

Estradiol alters only GAD67 mRNA levels in ischemic rat brain with no consequent effects on GABA. / Joh, Hung Dong; Searles, Robin V.; Selmanoff, Michael; Alkayed, Nabil; Koehler, Raymond C.; Hurn, Patricia D.; Murphy, Stephanie J.

In: Journal of Cerebral Blood Flow and Metabolism, Vol. 26, No. 4, 04.2006, p. 518-526.

Research output: Contribution to journalArticle

Joh, Hung Dong ; Searles, Robin V. ; Selmanoff, Michael ; Alkayed, Nabil ; Koehler, Raymond C. ; Hurn, Patricia D. ; Murphy, Stephanie J. / Estradiol alters only GAD67 mRNA levels in ischemic rat brain with no consequent effects on GABA. In: Journal of Cerebral Blood Flow and Metabolism. 2006 ; Vol. 26, No. 4. pp. 518-526.
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