Life expectancy, antagonistic pleiotropy, and the testis of dogs and men

BACKGROUND. Prostate cancer and benign prostatic hyperplasia are important age-related prostatic diseases that are under the influence of testicular h ormones. However, the disparity between male and female Life expectancy wit hin the human population cannot be explained solely by the prevalence of pr ostatic disease-related mortality. The purpose of this paper is to explore the possibility that the testis exerts a detrimental effect on life span. METHODS. First, we review previously published and unpublished data on the influence of the testis on the life span of dogs and men. Aging in pet dogs and men is then discussed in terms of evolutionary theory, emphasizing the significance of a prolonged postreproductive life span and possible conseq uences of late-acting deleterious genes in these two species. Finally, we p resent preliminary data that orchiectomy can reduce DNA damage within the b rain of elderly male dogs. RESULTS AND CONCLUSIONS. Taken together, these observations raise the intri guing possibility that interventions to antagonize the testis might have mu ch broader therapeutic applications that will extend well beyond the treatm ent of prostate cancer. (C) 2000 Wiley-Liss, Inc.