OBJECTIVENitric oxide (NO) is a key factor for penile erection. Its generation is mainly regulated by nitric oxide synthase (NOS), while both phospho-Erkl/2 (P-Erkl/2) and phospho-Aktl (P-Aktl) can affect the expression and activity of NOS and consequently penile erection. This experiment aimed to study the expressions of P-Erkl/2 and P-Aktl in the corpus cavernosum and their possible roles in erectile dysfunction in aged rats.

METHODSWe included 10 two-month-old male SD rats in Group A and another 10 eighteen-month-old ones in Group B, measured the levels of serum testosterone, and detected the expressions of P-Erkl/2 and P-Aktl in the corpus cavernosum by immunohistochemistry and RT-PCR.

RESULTSCompared with Group A, Group B showed a significantly decreased level of serum testosterone (9.57 +/- 1.57 nmol/L vs 4.73 +/- 0.94 nmol/L, P < 0.05), and remarkably increased mRNA expressions of P-Erk1 and P-Erk2 and protein expression of P-Erkl/2 (0.47 +/- 0.09, 0.61 +/- 0.11 and 7.50 +/- 1.81 vs 0.95 +/- 0.06, 0.92 +/- 0.05 and 32.09 +/- 8.45, P < 0.05). But there were no significant differences in the mRNA and protein expressions of P-Akt1 between the two groups (0.97 +/- 0.04 and 11.67 +/- 5.61 vs 0.94 +/- 0.05 and 10.93 +/- 3.06, P > 0.05).

CONCLUSIONThe overexpression of P-Erk1/2 in the corpus cavernous may be one of the important mechanisms of aging-related erectile dysfunction.