biostudies-literatureFarina MGNational Institute of Neurological Disorders and StrokeNational Center for Advancing Translational SciencesNorges ForskningsrådNCRR NIH HHSNINDS NIH HHS2858-2870https://www.ebi.ac.uk/biostudies/studies/S-EPMC9006438biostudies-literatureUnknown62(11)<h4>Objective</h4>The astroglial enzyme glutamine synthetase (GS) is deficient in small loci in the brain in adult patients with different types of focal epilepsy; however, the role of this deficiency in the pathogenesis of epilepsy has been difficult to assess due to a lack of sufficiently sensitive and specific animal models. The aim of this study was to develop an in vivo approach for precise and specific deletions of the GS gene in the postnatal brain.<h4>Methods</h4>We stereotaxically injected various adeno-associated virus (AAV)-Cre recombinase constructs into the hippocampal formation and neocortex in 22-70-week-old GS^flox/flox mice to knock out the GS gene in a specific and focal manner. The mice were subjected to seizure threshold determination, continuous video-electroencephalographic recordings, advanced in vivo neuroimaging, and immunocytochemistry for GS.<h4>Results</h4>The construct AAV8-glial fibrillary acidic protein-green fluorescent protein-Cre eliminated GS in >99% of astrocytes in the injection center with a gradual return to full GS expression toward the periphery. Such focal GS deletion reduced seizure threshold, caused spontaneous recurrent seizures, and diminished functional connectivity.<h4>Significance</h4>These results suggest that small loci of GS deficiency in the postnatal brain are sufficient to cause epilepsy and impaired functional connectivity. Additionally, given the high specificity and precise spatial resolution of our GS knockdown approach, we anticipate that this model will be extremely useful for rigorous in vivo and ex vivo studies of astroglial GS function at the brain-region and single-cell levels.EpilepsiaSmall loci of astroglial glutamine synthetase deficiency in the postnatal brain cause epileptic seizures and impaired functional connectivity.PMC9006438NS070824RR024139UL1 RR024139R01 NS109062K08 NS058674R21 NS109734NS109062NS058674NS109734240844R01 NS070824Parent MFarina MGDerbin MSandhu MRSSanganahalli BGEid TDanbolt NCWang HZaveri HPZhou YDhaher RHyder FfalseSmall loci of astroglial glutamine synthetase deficiency in the postnatal brain cause epileptic seizures and impaired functional connectivity.<h4>Objective</h4>The astroglial enzyme glutamine synthetase (GS) is deficient in small loci in the brain in adult patients with different types of focal epilepsy; however, the role of this deficiency in the pathogenesis of epilepsy has been difficult to assess due to a lack of sufficiently sensitive and specific animal models. The aim of this study was to develop an in vivo approach for precise and specific deletions of the GS gene in the postnatal brain.<h4>Methods</h4>We stereotaxically injected various adeno-associated virus (AAV)-Cre recombinase constructs into the hippocampal formation and neocortex in 22-70-week-old GS^flox/flox mice to knock out the GS gene in a specific and focal manner. The mice were subjected to seizure threshold determination, continuous video-electroencephalographic recordings, advanced in vivo neuroimaging, and immunocytochemistry for GS.<h4>Results</h4>The construct AAV8-glial fibrillary acidic protein-green fluorescent protein-Cre eliminated GS in >99% of astrocytes in the injection center with a gradual return to full GS expression toward the periphery. Such focal GS deletion reduced seizure threshold, caused spontaneous recurrent seizures, and diminished functional connectivity.<h4>Significance</h4>These results suggest that small loci of GS deficiency in the postnatal brain are sufficient to cause epilepsy and impaired functional connectivity. Additionally, given the high specificity and precise spatial resolution of our GS knockdown approach, we anticipate that this model will be extremely useful for rigorous in vivo and ex vivo studies of astroglial GS function at the brain-region and single-cell levels.2021-01-01T00:00:00Z2021 Nov2024-10-17T18:37:31.496Z2024-10-17T18:37:31.496ZS-EPMC90064383453623310.1111/epi.17072