Transcriptomic Analysis Corroborates the New Radial Model of the Mouse Pallial Amygdala

The mammalian amygdala is located in the temporal lobe of the telencephalon and plays a key role in limbic processing. Recently, our group proposed a radial morphological model to understand the glutamatergic (pallial) part of this nuclear complex in terms of separate progenitor domains. This model explains the amygdala region as consisting of several adjacent developmental radial progenitor units, disposing their distinct periventricular, intermediate, and superficial strata from the ventricle to the pial surface. It was expected that cell populations belonging to specific progenitor domains would present greater molecular similarity to each other than to neighboring developmental units. In this work, we aim to corroborate the existence of several radial domains in the pallial amygdala at the transcriptomic level. snRNAseq experiments in the amygdala of adult mice of both sexes indicated that at low resolution, the whole pallial amygdala was found to divide into two super-radial domains distinguished by differential expression of Slc17a6 and Slc17a7; the former partly imitates molecularly the subpallial (output) amygdalar regions, whereas the rest of the pallial amygdala is molecularly more akin to the surrounding cortical areas. In addition, our snRNAseq transcriptomic analysis fully supports the postulated amygdalar radial model of four main radial domains. Amygdalar region was microdissected from entire whole brains from adult mice, two males, two females. We used microsurgical knives under a dissection microscope (Leica S91) in ice-cold Sigma-Aldrich Dulbecco’s Phosphate Buffered Saline, without calcium and magnesium. The dissected tissue was frozen in liquid nitrogen and stored at -80ºC until used. Nuclei were isolated using the Minute™ single nucleus isolation kit designed for neuronal tissue/cells (Cat# BN-020, Invent Biotechnologies). Nuclei suspensions from each adult sample (AMM_A, AF_2, AM_2, AM_3) was diluted to an appropriate concentration and used as input to the 10X Chromium platform, using 10x Genomics Chromium controller plus Chromium Single Cell products for snRNAseq experiments.