TESTICULAR STEROIDOGENESIS IN THE AGING BROWN NORWAY RAT

In seeking an animal model of age-associated changes in the male repro ductive tract, we examined the effects of age on the health and testic ular steroidogenic activity of the Brown Norway rat, with comparisons made to the Sprague-Dawley rat. When perfused in vitro under condition s of maximally stimulating luteinizing hormone significant age-associa ted reductions were seen in testosterone production by testes of Sprag ue-Dawley rats of 21-24 months of age and by testes of Brown Norway ra ts of 18-30 months of age. Decreases in the capacity of the testes to produce testosterone were reflected in age-associated decreases in bot h serum testosterone and in testosterone concentration within the semi niferous tubule fluid. In contrast to the Sprague-Dawley rat, changes in steroidogenic activity in the Brown Norway rat were not accompanied by the occurrence of pituitary adenomas, obesity, or testicular tumor s. This, along with its longevity, make the Brown Norway strain a high ly promising model for testicular aging.