Transcriptomically-guided pharmacological experiments in neocortical and hippocampal NPY-positive GABAergic interneurons

Abstract

Cortical GABAergic interneurons have been shown to fulfil important roles by inhibiting excitatory principal neurons. Recent transcriptomic studies have confirmed seminal discoveries that used anatomic and electrophysiological methods highlighting the existence of multiple different classes of GABAergic interneurons. Although some of these studies have emphasized that inter-regional differences may exist for a given class, the extent of such differences remains unknown. To address this problem, we used single-cell Patch-RNAseq to characterize neuropeptide Y (NPY)-positive GABAergic interneurons in superficial layers of the primary auditory cortex (AC) and in distal layers of area CA3 in mice. We found that more than 300 genes are differentially expressed in NPY-positive neurons between these two brain regions. For example, the AMPA receptor (AMPAR) auxiliary subunit Shisa9/CKAMP44 and the 5HT2a receptor (5HT2aR) are significantly higher expressed in auditory NPY-positive neurons. These findings guided us to perform pharmacological experiments that revealed a role for 5HT2aRs in auditory NPY-positive neurons. Specifically, although the application of 5HT led to a depolarization of both auditory and CA3 NPY-positive neurons, the 5HT2aR antagonist ketanserin only reversed membrane potential changes in auditory NPY-positive neurons. Our study demonstrates the potential of single-cell transcriptomic studies in guiding directed pharmacological experiments.

Transcriptional and cell type profiles of cortical brain regions showing ultradian cortisol rhythm dependent responses to emotional face stimulation

“…None of the tissues included in these studies overlaps with the fMRI mask we used for our differential expression analysis. In this regard it is also important to note that even the same neuronal cell type can have a different transcriptomic profile depending on the cortical region it is embedded in, indicating the possible loss of power using several different non-overlapping tissues ( Beerens et al, 2022 ). Another issue is that MDD enrichment was found when using one study by Girgenti et al (2021) , but not when using the MDD gene set as defined by the study by Gandal et al (2018) .…”

Transcriptional and cell type profiles of cortical brain regions showing ultradian cortisol rhythm dependent responses to emotional face stimulation

“…In this regard it is also important to note that even the same neuronal cell type can have a different transcriptomic profile depending on the cortical region it is embedded in, indicating the possible loss of power using several different non-overlapping tissues. 43 Another issue is that MDD enrichment was found when using one study by Girgenti et al, 20 but not when using the MDD gene set as defined by the study by Gandal et al 21 This further indicates the difficulty of comparing different brain tissues, especially given a lack of robust marker genes throughout tissue types (which was the case for the data by Girgenti et al). Although the study by Gandal et al lists correlated log2 fold change in differentially expressed genes across disorders, and results from this study that are shared amongst different brain areas and diseases might be more robust, there is only one gene that satisfies the condition of having an FDR-corrected p-value < 0.05 in all five disorders (gene: CRH).…”