Cross-modal reaction of auditory and visual cortices after long-term bilateral hearing deprivation in the rat

Abstract

Visual cortex (VC) over-activation analysed by evoked responses has been demonstrated in congenital deafness and after longterm acquired hearing loss in humans. However, permanent hearing deprivation has not yet been explored in animal models. Thus, the present study aimed to examine functional and molecular changes underlying the visual and auditory cross-modal reaction. For such purpose, we analysed cortical visual evoked potentials (VEPs) and the gene expression (RT-qPCR) of a set of markers for neuronal activation (c-Fos) and activity-dependent homeostatic compensation (Arc/Arg3.1). To determine the state of excitation and inhibition, we performed RT-qPCR and quantitative immunocytochemistry for excitatory (receptor subunits GluA2/3) and inhibitory (GABAA-α1, GABAB-R2, GAD65/67 and parvalbumin-PV) markers. VC over-activation was demonstrated by a significant increase in VEPs wave N1 and by up-regulation of the activity-dependent early genes c-Fos and Arc/Arg3.1 (thus confirming, by RT-qPCR, our previously published immunocytochemical results). GluA2 gene and protein expression were significantly increased in the auditory cortex (AC), particularly in layers 2/3 pyramidal neurons, but inhibitory markers (GAD65/67 and PV-GABA interneurons) were also significantly upregulated in the AC, indicating a concurrent increase in inhibition. Therefore, after permanent hearing loss in the rat, the VC is not only over-activated but also potentially balanced by homeostatic regulation, while excitatory and inhibitory markers remain imbalanced in the AC, most likely resulting from changes in horizontal intermodal regulation.

Comparing the effects of transcranial alternating current and temporal interference (tTIS) electric stimulation through whole-brain mapping of c-Fos immunoreactivity

“…c-Fos has been successfully used to determine the neuronal effects of tTIS in the central nervous system (da Silva et al, 2014 ; Grossman et al, 2017 ). In our laboratory, we have used c-Fos as an activity marker as well as MATLAB mapping in previous experimental approaches (Clarkson et al, 2010 ; Lamas et al, 2017 ; Pernia et al, 2017 , 2020 ). And while our non-invasive approach should not induce severe tissue damage, we also assessed microglial reactivity by measuring Iba1 immunocytochemistry and neuronal preservation through Nissl staining.…”

Anatomy of hypothalamic and diencephalic nuclei involved in seasonal fertility regulation in ewes

“…Thus, in the present study, we provide a cytoarchitectonic guide for a more precise microdissection of SFR nuclei, enabling researchers to collect more appropriate samples for conventional proteomic or genomic techniques, individual cell sequencing or chemical analysis of hormones, transcription factors, and peptides. Preparing serial sagittal sections after micro-dissection enables to confirm the appropriate extracted areas, as previously we reported in the rat ( 53 ).…”

Effects of Multisession Anodal Electrical Stimulation of the Auditory Cortex on Temporary Noise-Induced Hearing Loss in the Rat

“…Glial reaction, both for IBA-1 and GFAP, was delimited on the auditory cortices (data not shown) as previously described by our group. To analyze the state of preservation of the temporal auditory area, after multisession protocol, alternate serial sections of brains from the ES group were stained for Nissl and for GAD 67 monoclonal mouse antibody (Merck Millipore #MAB5406 clone 1G10.2 RRID: AB_2278725 ) diluted at 1:1,000 TBS 0.05 M + Triton-Tx 0.3% according to the protocol previously described in Pernia et al (2020) ( Figure 2 ).…”