Ovariectomy attenuates phenotypes related to Alzheimer's disease in a preclinical mouse model and in C57BL/6 J mice

Women are at higher risk for Alzheimer's disease (AD) than men and hormonal changes during perimenopause are considered a risk factor. The relationship between ovarian hormones and AD has been explored using AD animal models, especially through ovariectomy (OVX) in established AD models. The link between early-stage AD and ovarian hormones, however, remains unclear, largely due to the lack of suitable animal models. Appropriate models for studying early-stage AD pathology, treatment, and prevention are critically needed. The App knock-in mouse model, which carries a single amyloid precursor protein (App) gene mutation, effectively reproduces early amyloid AD pathology. To elucidate the relationship between ovarian hormone deficiency and the behavioral phenotypes of a preclinical AD model, we applied a comprehensive behavioral test battery to this mouse model with bilateral OVX. The App mutation reduced anxiety-like behavior and impaired performance in the fear memory task. OVX restored the anxiety-like behavior of the App mutation mice to a level comparable to that in wild-type (WT) mice. Furthermore, OVX enhanced performance in a fear memory task in both genotypes and reduced amyloid-β staining in WT mice. Together, these findings suggest that OVX attenuates AD-related phenotypes in a preclinical AD model and in C57BL/6 J WT mice.