Conclusion
Endogenous H2S production was significantly decreased in the diabetic ED rats' penile tissues due to downregulated expression of the CAT/3-MST and DAO/3-MST pathways and low activities of CBS and CSE.
Methods
Experimental rats were randomly divided into normal control group, apomorphine (APO)-positive group and APO-negative group. Primary rat corpus cavernosum smooth muscle cells (CCSMCs) and aortic endothelial cells (AECs) were isolated and cultured in vitro under 3 different conditions: normal glucose (NG) condition, high glucose (HG) condition, and osmotic control (OC) condition. Main outcome measures: Erectile function; H2S concentrations in plasma or penile tissues; expression of H2S-generating enzymes and endogenous H2S production in penile tissues, CCSMCs, and AECs.
Results
Erectile function was significantly decreasedin the APO-negative group. In addition to significantly decreased expression of cysteine aminotransferase (CAT), d-amino acid oxidase (DAO), and 3-mercaptopyruvate sulfurtransferase (3-MST), the H2S concentrations in plasma and penile tissues and endogenous H2S production were significantly decreased in the APO-negative group. Endogenous H2S production by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) decreased to the same levels in the APO-negative and APO-positive groups as that in the normal control group. However, CBS and CSE expression remained unchanged in the 3 groups. Under HG conditions, H2S-generating enzyme expression in AECs did not change, while CAT, DAO, and 3-MST expression in CCSMCs was significantly decreased. In both cell types, H2S production by these enzymes was decreased in the HG group.