Noise exposure alters MMP9 and brevican expression in the rat primary auditory cortex

Abstract

Background: This study aimed to investigate the changes in molecules related to perineuronal nets (PNNs) and synaptic transporters in the primary auditory cortices of rats with noise-induced hearing loss. Female Sprague-Dawley rats at postnatal day 7 were divided into the noise and control groups. Four hours of 115 dB SPL white noise was delivered for 10 days to the noise group. Thirty days after noise exposure, the primary auditory cortex and the inferior colliculus were harvested. The expression levels of vesicular glutamatergic transporter (VGLUT)1, VGLUT2, vesicular GABA transporter (VGAT), glutamate decarboxylase (GAD)67, brevican, aggrecan, MMP9, and MMP14 were evaluated using real-time reverse transcription polymerase chain reaction or western blot. An immunofluorescence assay was conducted to assess parvalbumin (PV), Wisteria floribunda agglutinin (WFA), and brevican. The immune-positive cells were counted in the primary auditory cortex. Results: The expression level of VGLUT1 in the primary auditory cortex was decreased in the noise group. The expression level of VGLUT2 in the inferior colliculus was elevated in the noise group. The expression levels of brevican and PV + WFA in the primary auditory cortex were decreased in the noise group. The expression level of MMP9 in the primary auditory cortex was increased in the noise group. Conclusion: Noise-induced hearing loss during the precritical period impacted PNN expression in the primary auditory cortex. Increased MMP9 expression may have contributed to the decrease in brevican expression. These changes were accompanied by the attenuation of glutamatergic synaptic transporters.

Effect of acute noise trauma on the gene expression profile of the hippocampus

“…Six to eight hours after the ABR measurement, all rats were sacrificed and their hippocampi (n = 15 per group) and primary temporal cortices (n = 6 per group) were harvested. The euthanasia was conducted by carbon dioxide inhalation with flow rate of 5–6 L/min in 25.40 ×48.26 ×22.86 cm size cage, as previously described [ 17 ]. The dorsal cornu ammonis 3 (CA3) region of the rat hippocampus was located in a reference atlas, and identical tissue samples were dissected from adjacent regions of CA2 and the dentate gyrus [ 18 ]).…”

Differential Expression of miRNAs and Their Predicted Target Pathways in Cochlear Nucleus Following Chronic Noise Exposure in Rats

“…The chondroitin sulfate proteoglycans (CSPGs), such as brevicans and neurocans, are composed of PNs [ 4 ]. Changes in the PNs following noise exposure have been reported in the primary auditory cortex [ 5 , 6 ]. However, the changes in PNs or CSPGs have not been explored in the auditory brainstem of noise-induced hearing loss model.…”

“…Previous studies demonstrated the changes of CSPGs including brevican in auditory nervous system following noise-induced hearing loss [ 5 , 6 ]. The mediating role of miRNAs were suggested for the changes of CSPGs in visual cortex [ 14 ].…”