Abstract
Age-related depletion of androgens in men results in functional impairments in androgen-responsive tissues, such as the brain, resulting in increased risk for Alzheimer's disease. To investigate the relationship between normal age-related hormone loss and Alzheimer's disease risk, we evaluated the brain and serum levels of androgens and estrogen in aging male rats. We observed that increasing age was associated with a significant reduction in brain levels of the potent androgen dihydrotestosterone and a trend toward decreased testosterone. Brain levels of soluble beta-amyloid were observed to increase with age. Collectively, these findings highlight differences in brain and circulating levels of androgens during aging, and identify an inverse correlation with beta-amyloid levels that may be relevant to Alzheimer's disease risk.