Age- and lobe-specific responses of the brown Norway rat prostate to androgen.

We examined the effects of age and of increasing concentrations of testosterone on the wet weight, protein content, cell number, and cell size of the ventral, dorsal, and lateral lobes of the Brown Norway rat prostate. Young (3 mo of age) and aged (15, 17, and 21 mo of age) rats received implants of increasing sizes of testosterone-filled Silastic capsules for 3 mo. Wet weights of the prostate were the same in untreated young (6-mo-old) and aged (18-24-mo-old) rats. Testosterone administration resulted in serum testosterone concentrations ranging from physiologic to superphysiologic. Dose-dependent increases in wet weights and protein contents were seen in the ventral, dorsal, and lateral prostatic lobes of both young and aged rats. For each given dose of testosterone, including doses that resulted in serum testosterone concentrations within the physiologic range, the weights and protein contents of the dorsal and lateral lobes were greater in old (24-mo-old) than in young (6-mo-old) rats, indicating an effect of age in these lobes. In contrast, ventral prostate weights and protein contents increased equivalently in young and aged rats with increasing testosterone concentration. DNA content, a measure of cell number, increased significantly in the dorsal and lateral lobes as a function of testosterone dose and age, but in the ventral lobe did not differ with testosterone dose or age. Quantitative morphologic analyses showed significant hypertrophy of epithelial cells throughout each of the three lobes in both young and aged rats treated with testosterone. Taken together, these results indicate that the prostate of Brown Norway rats shows age and lobe-specific responses to androgen with respect to wet weight, protein content, cell number, and cell morphology.