Figure 6.

cAMP (A) and testosterone production (B and C) by Leydig cells isolated from 4-month-old (young) and 24-month-old (old) rats that were treated with BSO or vehicle (PBS) for 7 d. For cAMP assays (A), Leydig cells were incubated with LH (100 ng/ml) and the phosphodiesterase inhibitor isobutyl-methylxanthine (100 μm) for 30 min. For testosterone assays, cells were incubated with dbcAMP (2 mm, B) or 25-HC (12.5 μm, C) for 2 h. The data are expressed as mean ± sem of six animals per group. *, Significantly different from cells isolated from age-matched control animals at P < 0.05.