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Changes in the expression of GABAA receptor subunit mRNAs in parahippocampal areas after kainic acid induced seizures.

ABSTRACT: The parahippocampal areas including the subiculum, pre- and parasubiculum, and notably the entorhinal cortex (EC) are intimately involved in the generation of limbic seizures in temporal lobe epilepsy. We investigated changes in the expression of 10 major GABAA receptor subunit mRNAs in subfields of the ventral hippocampus, ventral subiculum, EC, and perirhinal cortex (PRC) at different intervals (1, 8, 30, and 90 days) after kainic acid (KA)-induced status epilepticus priming epileptogenesis in the rat. The most pronounced and ubiquitous changes were a transient (24 h after KA only) down-regulation of ?2 mRNA and lasting decreases in subunit ?5, ?3, and ? mRNAs that were prominent in all hippocampal and parahippocampal areas. In the subiculum similarly as in sectors CA1 and CA3, levels of subunit ?1, ?2, ?4, and ?2 mRNAs decreased transiently (1 day after KA-induced status epilepticus). They were followed by increased expression of subunit ?1 and ?3 mRNAs in the dentate gyrus (DG) and sectors CA1 and CA3, and subunit ?1 also in the EC layer II (30 and 90 days after KA). We also observed sustained overexpression of subunits ?4 and ?2 in the subiculum and in the Ammon's horn. Subunit ?2 mRNA was also increased in sector CA1 at the late intervals after KA. Taken together, our results suggest distinct regulation of mRNA expression for individual GABAA receptor subunits. Especially striking was the wide-spread down-regulation of the often peri- or extrasynaptically located subunits ?5 and ?. These subunits are often associated with tonic inhibition. Their decrease could be related to decreased tonic inhibition or may merely reflect compensatory changes. In contrast, expression of subunit ?4 that may also mediate tonic inhibition when associated with the ?-subunit was significantly upregulated in the DG and in the proximal subiculum at late intervals. Thus, concomitant up-regulation of subunit ?2, ?1 and ?4 mRNAs (and loss in ?-subunits) ultimately indicates significant rearrangement of GABAA receptor composition after KA-induced seizures.

SUBMITTER: Drexel M

PROVIDER: S-EPMC3776158 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Changes in the expression of GABAA receptor subunit mRNAs in parahippocampal areas after kainic acid induced seizures.

Drexel Meinrad M Kirchmair Elke E Sperk Günther G

Frontiers in neural circuits 20130918

The parahippocampal areas including the subiculum, pre- and parasubiculum, and notably the entorhinal cortex (EC) are intimately involved in the generation of limbic seizures in temporal lobe epilepsy. We investigated changes in the expression of 10 major GABAA receptor subunit mRNAs in subfields of the ventral hippocampus, ventral subiculum, EC, and perirhinal cortex (PRC) at different intervals (1, 8, 30, and 90 days) after kainic acid (KA)-induced status epilepticus priming epileptogenesis in ...[more]

PMID: 24065890

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Dataset Information

Changes in the expression of GABAA receptor subunit mRNAs in parahippocampal areas after kainic acid induced seizures.

Publications

Changes in the expression of GABAA receptor subunit mRNAs in parahippocampal areas after kainic acid induced seizures.

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