Abnormalities in cortical interneuron subtypes in ephrin‐B mutant mice. (10th July 2018)

• Record Type: Journal Article
• Authors: Talebian, Asghar; Britton, Rachel; Henkemeyer, Mark
• Is Part Of: European journal of neuroscience. Volume 48:Number 2(2018)
• Page Start: 1803
• Page End: 1817
• Publication Date: 2018-07-10
• Subjects: CA1 -- cortex -- Eph‐Ephrin bidirectional signaling -- hippocampus -- interneuron subtypes; Nervous system -- Periodicals; 612.8
• DOI: 10.1111/ejn.14022
• Languages: English
• ISSNs: 0953-816X

Abstract

Abstract: To explore roles for ephrin‐B/EphB signaling in cortical interneurons, we previously generated ephrin‐B ( Efnb1/b2/b3 ) conditional triple mutant ( TM lz ) mice using a Dlx1/2.Cre inhibitory neuron driver and green fluorescent protein (GFP) reporters for the two main inhibitory interneuron groups distinguished by expression of either glutamic acid decarboxylase 1 (GAD1; GAD67‐GFP) or 2 (GAD2; GAD65‐GFP). This work showed a general involvement of ephrin‐B in migration and population of interneurons into the embryonic neocortex. We now determined whether specific interneurons are selectively affected in the adult brains of TM lz .Cre mice by immunostaining with antibodies that identify the different subtypes. The results indicate that GAD67‐GFP‐expressing interneurons that also express parvalbumin (PV), calretinin (CR) and, to a lesser extent, somatostatin (SST) and Reelin (Rln) were significantly reduced in the cortex and hippocampal CA1 region in TM lz .Cre mutant mice. Neuropeptide Y (NPY) interneurons that also express GAD67‐GFP were reduced in the hippocampal CA1 region, but much less so in the cortex, although these cells exhibited abnormal cortical layering. In GAD65‐GFP‐expressing interneurons, CR subtypes were reduced in both cortex and hippocampal CA1 region, whereas Rln interneurons were reduced exclusively in hippocampus, and the numbers of NPY and vasoactive intestinal polypeptide (VIP) subtypes appeared normal. PV and CR subtype interneurons in TM lz .Cre mice also exhibited reductions in their perisomatic area, suggesting abnormalities in dendritic/axonal complexity. Altogether, our data indicate that ephrin‐B expression within forebrain interneurons is required in specific subtypes for their normal population, cortical layering and elaboration of cell processes. Abstract : Many different interneuron subtypes in the cortex and hippocampus are altered in ephrin‐B inhibitory neuron mutant mice. We utilized tdTomato fluorescence to identify inhibitory neurons exposed to Cre recombinase (red), GFP fluorescence to identify either GAD67 or GAD65 expressing inhibitory neurons (green) and antibodies to identify specific interneuron subtypes (purple). Shown is a confocal image of merged tdTomato, GAD67‐GFP and somatostatin signals identifying interneurons in the cortex.