Tags

Type your tag names separated by a space and hit enter

Phosphatase inhibition prevents the activity-dependent trafficking of GABAA receptors during status epilepticus in the young animal.
Epilepsia. 2015 Sep; 56(9):1355-65.E

Abstract

OBJECTIVES

To determine if the activity-dependent trafficking of γ2 subunit-containing γ-aminobutyric acid type A receptors (GABAA Rs) that has been observed in older animals and posited to contribute to benzodiazepine pharmacoresistance during status epilepticus (SE) is age-dependent, and to evaluate whether blockade of protein phosphatases can inhibit or reverse the activity-dependent plasticity of these receptors.

METHODS

The efficacy and potency of diazepam 0.2-10 mg/kg administered 3 or 60 min after the onset of a lithium/pilocarpine-induced seizure in postnatal day 15-16 rats was evaluated using video-electroencephalography (EEG) recordings. The surface expression of γ2 subunit-containing GABAA Rs was assessed using a biotinylation assay, and GABAA R-mediated miniature inhibitory postsynaptic currents (mIPSCs) were recorded using whole-cell patch-clamp recording techniques from dentate granule cells in hippocampal slices acutely obtained 60 min after seizure onset (SE-treated). The effect of the protein phosphatase inhibitors FK506 and okadaic acid (OA) on the surface expression of these receptors was determined in organotypic slice cultures exposed to high potassium and N-methyl-d-aspartate (NMDA) or in SE-treated slices.

RESULTS

Diazepam terminated seizures of 3 min but not 60 min duration, even at the highest dose. In the SE-treated slices, the surface expression of γ2 subunit-containing GABAA Rs was reduced and the amplitude of the mIPSCs was diminished. Inhibition of protein phosphatases prevented the activity-induced reduction of the γ2 subunit-containing GABAA Rs in organotypic slice cultures. Furthermore, treatment of SE-treated slices with FK506 or OA restored the surface expression of the γ2 subunit-containing GABAA Rs and the mIPSC amplitude.

SIGNIFICANCE

This study demonstrates that the plasticity of γ2 subunit-containing GABAA Rs associated with the development of benzodiazepine resistance in young and adult animals is similar. The findings of this study suggest that the mechanisms regulating the activity-dependent trafficking of GABAA Rs during SE can be targeted to develop novel adjunctive therapy for the treatment of benzodiazepine-refractory SE.

Authors+Show Affiliations

Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A.Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A.Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A.Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A.Department of Pediatrics, University of Virginia Health System, Charlottesville, Virginia, U.S.A.Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A.Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A.Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A. Department of Pediatrics, University of Virginia Health System, Charlottesville, Virginia, U.S.A.

Pub Type(s)

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

Language

eng

PubMed ID

26248944

Citation

Joshi, Suchitra, et al. "Phosphatase Inhibition Prevents the Activity-dependent Trafficking of GABAA Receptors During Status Epilepticus in the Young Animal." Epilepsia, vol. 56, no. 9, 2015, pp. 1355-65.
Joshi S, Rajasekaran K, Hawk KM, et al. Phosphatase inhibition prevents the activity-dependent trafficking of GABAA receptors during status epilepticus in the young animal. Epilepsia. 2015;56(9):1355-65.
Joshi, S., Rajasekaran, K., Hawk, K. M., Brar, J., Ross, B. M., Tran, C. A., Chester, S. J., & Goodkin, H. P. (2015). Phosphatase inhibition prevents the activity-dependent trafficking of GABAA receptors during status epilepticus in the young animal. Epilepsia, 56(9), 1355-65. https://doi.org/10.1111/epi.13098
Joshi S, et al. Phosphatase Inhibition Prevents the Activity-dependent Trafficking of GABAA Receptors During Status Epilepticus in the Young Animal. Epilepsia. 2015;56(9):1355-65. PubMed PMID: 26248944.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Phosphatase inhibition prevents the activity-dependent trafficking of GABAA receptors during status epilepticus in the young animal. AU - Joshi,Suchitra, AU - Rajasekaran,Karthik, AU - Hawk,Kyle M, AU - Brar,Jasmit, AU - Ross,Brittany M, AU - Tran,Christine A, AU - Chester,Stephen J, AU - Goodkin,Howard P, Y1 - 2015/08/06/ PY - 2015/07/01/accepted PY - 2015/8/8/entrez PY - 2015/8/8/pubmed PY - 2016/4/30/medline KW - Benzodiazepine KW - FK506 KW - Okadaic acid KW - Phosphatase SP - 1355 EP - 65 JF - Epilepsia JO - Epilepsia VL - 56 IS - 9 N2 - OBJECTIVES: To determine if the activity-dependent trafficking of γ2 subunit-containing γ-aminobutyric acid type A receptors (GABAA Rs) that has been observed in older animals and posited to contribute to benzodiazepine pharmacoresistance during status epilepticus (SE) is age-dependent, and to evaluate whether blockade of protein phosphatases can inhibit or reverse the activity-dependent plasticity of these receptors. METHODS: The efficacy and potency of diazepam 0.2-10 mg/kg administered 3 or 60 min after the onset of a lithium/pilocarpine-induced seizure in postnatal day 15-16 rats was evaluated using video-electroencephalography (EEG) recordings. The surface expression of γ2 subunit-containing GABAA Rs was assessed using a biotinylation assay, and GABAA R-mediated miniature inhibitory postsynaptic currents (mIPSCs) were recorded using whole-cell patch-clamp recording techniques from dentate granule cells in hippocampal slices acutely obtained 60 min after seizure onset (SE-treated). The effect of the protein phosphatase inhibitors FK506 and okadaic acid (OA) on the surface expression of these receptors was determined in organotypic slice cultures exposed to high potassium and N-methyl-d-aspartate (NMDA) or in SE-treated slices. RESULTS: Diazepam terminated seizures of 3 min but not 60 min duration, even at the highest dose. In the SE-treated slices, the surface expression of γ2 subunit-containing GABAA Rs was reduced and the amplitude of the mIPSCs was diminished. Inhibition of protein phosphatases prevented the activity-induced reduction of the γ2 subunit-containing GABAA Rs in organotypic slice cultures. Furthermore, treatment of SE-treated slices with FK506 or OA restored the surface expression of the γ2 subunit-containing GABAA Rs and the mIPSC amplitude. SIGNIFICANCE: This study demonstrates that the plasticity of γ2 subunit-containing GABAA Rs associated with the development of benzodiazepine resistance in young and adult animals is similar. The findings of this study suggest that the mechanisms regulating the activity-dependent trafficking of GABAA Rs during SE can be targeted to develop novel adjunctive therapy for the treatment of benzodiazepine-refractory SE. SN - 1528-1167 UR - https://www.unboundmedicine.com/medline/citation/26248944/Phosphatase_inhibition_prevents_the_activity_dependent_trafficking_of_GABAA_receptors_during_status_epilepticus_in_the_young_animal_ L2 - https://doi.org/10.1111/epi.13098 DB - PRIME DP - Unbound Medicine ER -