Figure 1.

Serum glucocorticoid (a) and testosterone (b) concentrations of young control (6-month-old), chronically stressed and old (21-month-old) Brown Norway rats. The serum corticosterone levels of the stress group were increased significantly compared with the young control group (a); serum testosterone levels in both the stress and the old group were decreased significantly compared with the young control group (b). The results represent the mean±s.e.m. * P<0.05 compared with the Young group.