Department of Otorhinolaryngology-Head and Neck Surgery, Chung-Ang University College of Medicine, 102 Heukseok-ro, Dongjak-gu, Seoul, 06973, Republic of Korea.
Department of Biomedical Sciences, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.
Behav Brain Res. 2019 Oct 17;372:112069. doi: 10.1016/j.bbr.2019.112069. Epub 2019 Jul 2.
Although epidemiological studies have identified an association between hearing loss and cognitive impairment, there is a lack of biological evidence detailing the mechanisms underlying this association. The present study investigated the effects of hearing loss on cognitive impairment using an at-risk model. In this animal model, amyloid-β (Aβ) was administered to the brain to such an extent that it did not cause cognitive impairments but made the brain vulnerable to risk factors. This study included four experimental groups based on hearing level and Aβ administration. Behavioral tests were conducted to evaluate cognitive function, and synaptic protein levels were measured in the hippocampus and prefrontal cortex. The group with hearing loss and Aβ administration showed significantly greater deficits on cognitive tests associated with the hippocampus than the other three groups (only Aβ administration, only hearing loss, and without hearing loss or Aβ administration). The hearing loss and Aβ administration group also had significantly lower levels of synaptic proteins in the hippocampus than the other groups. The present results suggest that hearing loss may act as a risk factor for cognitive impairment in Alzheimer's disease. Additionally, the present findings indicate hearing loss may cause hippocampal synapses to be more vulnerable to Aβ-induced damage.
虽然流行病学研究已经确定了听力损失与认知障碍之间的关联，但缺乏详细描述这种关联的生物学证据。本研究使用高危模型探讨了听力损失对认知障碍的影响。在这种动物模型中，向大脑中注入足够量的淀粉样蛋白-β（Aβ），使其不会引起认知障碍，但会使大脑易受风险因素的影响。本研究基于听力水平和 Aβ 给药将动物分为四个实验组。通过行为测试评估认知功能，测量海马体和前额叶皮层中的突触蛋白水平。与其他三组（仅 Aβ 给药、仅听力损失、无听力损失或 Aβ 给药）相比，听力损失和 Aβ 给药组在与海马体相关的认知测试中表现出明显更大的缺陷。听力损失和 Aβ 给药组的海马体中的突触蛋白水平也明显低于其他组。本研究结果表明，听力损失可能是阿尔茨海默病认知障碍的一个风险因素。此外，本研究结果表明，听力损失可能导致海马体突触更容易受到 Aβ 诱导的损伤。
