{"title":"Abnormality in GABAergic postsynaptic transmission associated with anxiety in Bronx waltzer mice with an Srrm4 mutation","authors":"Yuka Shirakawa , Heng Li , Yuki Inoue , Hitomi Izumi , Yoshimi Kaga , Yu-ichi Goto , Ken Inoue , Masumi Inagaki","doi":"10.1016/j.ibneur.2023.12.005","DOIUrl":null,"url":null,"abstract":"<div><p>The homozygous <em>Bronx waltzer</em> (<em>bv</em>) mouse, which shows hearing impairment, also exhibits anxiety accompanied by a reduction in cortical parvalbumin (PV)-positive GABAergic interneurons. Recently, a mutation in splicing factor Ser/Arg repetitive matrix 4 (Srrm4) was found in <em>bv</em> mice. However, the cellular consequences of the <em>Srrm4</em> mutation for anxiety remain unknown. Here, we tested our hypothesis that <em>bv</em> mutant primarily affects interneurons through a cell-intrinsic pathology that leads to a reduction of interneurons and consequently causes anxiety. We found that the anxiety becomes apparent at 6 weeks of age in <em>bv/bv</em> mice. However, in situ hybridization revealed that <em>Srrm4</em> is not expressed in interneurons, but rather dominates in pyramidal neurons. In addition, the PV-positive GABAergic interneurons were not reduced in number in the <em>bv/bv</em> cortex when anxiety became evident. However, electrophysiological abnormality of GABAergic transmission from interneurons was concomitantly present. Pharmacological blockage of GABA<sub>A</sub> receptors revealed increased excitability in <em>bv/bv</em> mice, although no gross change occurred in the expression of an <em>Srrm4</em>-downstream gene, <em>Kcc2</em>, which regulates chloride flux upon GABAergic transmission. These findings suggest that the <em>bv</em>-associated <em>Srrm4</em> mutation mainly involves post-synaptic GABAergic transmission in the central nervous system, which may be associated with the anxiety phenotype in <em>bv/bv</em> mice.</p></div>","PeriodicalId":13195,"journal":{"name":"IBRO Neuroscience Reports","volume":null,"pages":null},"PeriodicalIF":2.0000,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2667242123022911/pdfft?md5=50b70548445f3fd37f8ded459a484f85&pid=1-s2.0-S2667242123022911-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"IBRO Neuroscience Reports","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2667242123022911","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"NEUROSCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
The homozygous Bronx waltzer (bv) mouse, which shows hearing impairment, also exhibits anxiety accompanied by a reduction in cortical parvalbumin (PV)-positive GABAergic interneurons. Recently, a mutation in splicing factor Ser/Arg repetitive matrix 4 (Srrm4) was found in bv mice. However, the cellular consequences of the Srrm4 mutation for anxiety remain unknown. Here, we tested our hypothesis that bv mutant primarily affects interneurons through a cell-intrinsic pathology that leads to a reduction of interneurons and consequently causes anxiety. We found that the anxiety becomes apparent at 6 weeks of age in bv/bv mice. However, in situ hybridization revealed that Srrm4 is not expressed in interneurons, but rather dominates in pyramidal neurons. In addition, the PV-positive GABAergic interneurons were not reduced in number in the bv/bv cortex when anxiety became evident. However, electrophysiological abnormality of GABAergic transmission from interneurons was concomitantly present. Pharmacological blockage of GABAA receptors revealed increased excitability in bv/bv mice, although no gross change occurred in the expression of an Srrm4-downstream gene, Kcc2, which regulates chloride flux upon GABAergic transmission. These findings suggest that the bv-associated Srrm4 mutation mainly involves post-synaptic GABAergic transmission in the central nervous system, which may be associated with the anxiety phenotype in bv/bv mice.