Figure 4. Serum testosterone levels and body weights. (A) Serum testosterone levels were significantly lower in 24Mon rats than in 6Mon rats. Supplementation of aged male rats with TP increased their serum testosterone concentrations to the level of 6Mon rats. (B) No differences in body weight were detected between 24Mon-TP and 24Mon rats. Data are expressed as the mean ± S.D. (n=12 rats/group). *P<0.01.