Luteinizing hormone modulates cognition and amyloid-beta deposition in Alzheimer APP transgenic mice

Until recently, the study of hormonal influences in Alzheimer disease was limited to the role of sex steroids. Despite numerous epidemiological studies supporting a protective role for estrogen in Alzheimer disease, recent studies show that estrogen administration in elderly women increases the risk of disease. Reconciling these contradictory reports, we previously hypothesized that other hormones of the hypothalamic-pituitary-gonadal axis, such as luteinizing hormone, may be involved in the onset and development of the disease. In this regard, luteinizing hormone is elevated in Alzheimer disease and is known to modulate amyloidogenic processing of amyloid-beta protein precursor. Therefore, in this study, to evaluate the therapeutic potential of luteinizing hormone ablation, we administered a gonadotropin-releasing hormone analogue, leuprolide acetate, to an aged transgenic mouse model of Alzheimer disease (Tg 2576) and measured cognitive Y-maze performance and amyloid-beta deposition after 3 months of treatment. Our data indicate that luteinizing hormone ablation significantly attenuated cognitive decline and decreased amyloid-beta deposition as compared to placebo-treated animals. Importantly, leuprolide acetate-mediated reduction of amyloid-beta correlated with improved cognition. Since both cognitive loss and amyloid-beta deposition are features of Alzheimer disease, leuprolide acetate treatment may prove to be a useful therapeutic strategy for this disease.