Effects of simvastatin on plasma lipoproteins and hearing loss in apolipoprotein E gene-deficient mice

Apolipoprotein E (ApoE) gene knockout (KO) mice develop hearing loss, as well as hair cell damage in the inner ear. Furthermore, the hearing loss and hair cell damage may be caused and exacerbated by hyperlipidemia and atherosclerosis. We are therefore seeking an effective treatment to protect the inner ear in ApoE-KO mice. ApoE-KO mice fed with an atherosclerotic diet were treated with simvastatin or with Strauss Heartdrops. The auditory brainstem responses were recorded, and plasma lipid levels and inner ear histology were examined. ApoE-KO and wild-type C57BL/6J mice fed with a normal chow diet served as controls. Compared to ApoE-KO mice fed only the atherosclerotic diet, ApoE-KO mice treated with simvastatin had no significant hearing loss and less severe atherosclerosis and hair cell damage in the inner ear. However, ApoE-KO mice treated with Strauss Heartdrops developed significant hearing loss and severe atherosclerosis and hair cell damage in the inner ear. These results demonstrate that statins may prevent hearing loss and inner ear damage in ApoE-KO mice by reducing the atherosclerotic lesions and levels of glucose, cholesterol, low-density lipoprotein, and triglyceride. Statins could be used to treat hearing loss associated with hyperlipidemia.