Effect of low androgen levels on the sulphur dioxide signalling pathway in rat penile corpus cavernosum

The aim of this study was to investigate the relationship between sulphur dioxide (SO₂) signalling pathway and the changes in erectile function under low androgen levels. Thirty‐six healthy male Sprague Dawley (SD) rats aged eight weeks were randomly divided into androgen replacement group, castration group and sham group. Rats in the androgen replacement group were subcutaneously injected with testosterone propionate at 3 mg/kg every other day postcastration. The maximum intracavernous pressure/mean arterial pressure (ICP_max/MAP) and the relative content of SO₂ in the penile corpus cavernosum were measured. The mRNA and protein expressions of aspartate aminotransferase (AAT1 and AAT2), cysteine oxidase (CDO), endothelial nitric oxide synthase (eNOS) and phosphorylation of endothelial nitric oxide synthase (P‐eNOS) were detected. ICP_max/MAP, P‐eNOS/eNOS and the level of SO₂ decreased significantly in the castration group compared to the other groups (p < 0.05). The expressions of mRNA and protein decreased significantly in the castration group compared to the androgen replacement group and the sham group (p < 0.05), while there was no significant difference between the androgen replacement group and sham group. Low androgen levels can inhibit erectile function by downregulating the SO₂ signalling pathway.