Effect of acute noise trauma on the gene expression profile of the hippocampus
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BMC Neuroscience Open Access
RESEARCH ARTICLE
Effect of acute noise trauma on the gene expression profile of the hippocampus Chang Ho Lee, Kyung Woon Kim, So Min Lee and So Young Kim*
Abstract Background: This study aimed to investigate the changes in the expression of hippocampal genes upon acute noise exposure. Methods: Three-week-old Sprague–Dawley rats were assigned to control (n = 15) and noise (n = 15) groups. White noise (2–20 kHz, 115 dB sound pressure level [SPL]) was delivered for 4 h per day for 3 days to the noise group. All rats were sacrificed on the last day of noise exposure, and gene expression in the hippocampus was analyzed using a microarray. Pathway analyses were conducted for genes that showed differential expression ≥ 1.5-fold and P ≤ 0.05 compared to the control group. The genes included in the putative pathways were measured using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Results: Thirty-eight upregulated genes and 81 downregulated genes were identified. The pathway analyses revealed that upregulated genes were involved in the cellular responses to external stimuli and immune system pathways. qRT-PCR confirmed the upregulation of the involved genes. The downregulated genes were involved in neuronal systems and synapse-related pathways, and qRT-PCR confirmed the downregulation of the involved genes. Conclusions: Acute noise exposure upregulated the expression of immune-related genes and downregulated the expression of neurotransmission-related genes in the hippocampus. Keywords: Hippocampus, Noise, Hearing loss, Microarray analysis, Genetic association studies Background Hearing loss has been suggested to be associated with cognitive deficits [1]. Although conflicting data have been reported for the bidirectional association or the weak contribution of peripheral hearing loss to cognitive dysfunction [2, 3], many clinical studies have confirmed the effect of peripheral hearing loss on cognitive dysfunction [1]. Auditory sensory deficits and accompanying disabilities, such as communication problems and social isolation, may alter the hippocampus and result in cognitive dysfunction in patients with chronic hearing loss. Intense noise exposure is known to cause permanent hearing loss and stress responses [4–6]. An increasing *Correspondence: [email protected] Department of Otorhinolaryngology, CHA University College of Medicine, 59 Yatap‑ro, Bundang‑gu, Seongnam 13496, Gyeonggi‑do, Korea
number of experimental studies have supported the association between noise exposure and cognitive dysfunction [7–9]. A study of a senescence-prone mouse model revealed that chronic noise exposure for 30 days reduced the activity of the Wnt signaling pathway and increased amyloid-beta accumulation and tau hyperphosphorylation in the hippocampus [9]. Similarly, a study of Wistar rats reported tau hyperphosphorylation and increased corticotropin-releasing factor levels after 30 days of noise exposure [7]. Although most previous studies have examined the effects of long-ter
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