OBJECTIVETo investigate the role of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) pathway in erectile dysfunction (ED) caused by the absence of testosterone (T).

METHODSWe randomly divided 30 eight-week-old healthy male SD rats into groups A (control) , B (castration), and C (castration + androgen replacement). The rats in groups B and C were castrated surgically, and those in C injected with T undecanoate (100 mg/kg) at 1 week after castration, while the others with 0.9% normal saline instead. At 1 month after treatment, we determined the serum T level, intracavernous pressure (ICP), and mean carotid arterial pressure (MAP) of the rats, and detected the expressions of ERK1/2 and endothelial nitric oxide synthase (eNOS) by Western blot.

RESULTSThe serum T level was significantly lower in group B ([1.27 ± 0.48] nmol/L) than in A ([17.14 ± 1.07] nmol/L) and C ([16.24 ± 1.90] nmol/L) (P < 0.05), and so were ICP and MAP (P < 0.05). The expression of ERK1/2 showed no statistically significant differences among the three groups (P > 0.05), that of phosphatase ERK1/2 was markedly higher while that of eNOS remarkably lower in group B than in A and C (both P < 0.05).

CONCLUSIONAndrogen replacement may improve the erectile function of castrated rats by regulating the ERK1/2 pathway.