GABA release and GAD67 mRNA expression in rat hippocampus following entorhinal cortex activation

Torkel Falkenberg, Nils Lindefors, William T. O'Connor, Olof Zachrisson, Francesca Camilli, Urban Ungerstedt

Research output: Contribution to journalArticlepeer-review

Abstract

This study investigate the effect of stimulation of glutamatergic afferents originating in the entorhinal cortex on possible changes of GABAergic transmission in the CA1 subregion of the hippocampus. Microdialysis was used to monitor extracellular GABA and in situ hybridization to measure levels of glutamic acid decarboxylase67 (GAD67) mRNA. A dose-dependent increase in extracellular levels of GABA in the dorsal CA1 subregion was detected following injection of 2.4 and 9.6 μg quisqualate into the lateral entorhinal cortex whereas 0.24 μg had no effect. The GABA increase was attenuated by local administration of tetrodotoxin (TTX), indicating neuronal origin. A 60% decrease and a 160% increase were seen in levels of GAD67 mRNA in the CA1 following injection of 0.24 and 9.6 μg quisqualate, respectively. This study provides evidence of an entorhinal cortex influenced stimulatory effect on GABAergic activity in the CA1. However, no direct relationship was found between stimulated GABA release and subsequently measured GAD67 mRNA levels. The increased GABA release and the apparent adaptive increase in GAD67 mRNA levels by the strongest stimulation may be due to an endogenous inhibitory neuroprotective response to an excitotoxic influence.

Original languageEnglish
Pages (from-to)413-416
Number of pages4
JournalMolecular Brain Research
Volume48
Issue number2
DOIs
Publication statusPublished - Sep 1997
Externally publishedYes

Keywords

  • γ-aminobutyric acid
  • CA1
  • Glutamic acid decarboxylase
  • Hybridization, in situ
  • Microdialysis
  • Quisqualate

Fingerprint

Dive into the research topics of 'GABA release and GAD67 mRNA expression in rat hippocampus following entorhinal cortex activation'. Together they form a unique fingerprint.

Cite this