O-β-N-acetylglucosaminidase on human erythrocytes as biomarker of oxidative stress in erectile disfunction patients

Background. Oxidative Stress (OS) plays an important role in pathophysiological process of Erectile Dysfunction (ED). eNOS is an emerging and important actor in promotion and maintenance of erection by phosphorylation of specific site (Ser-117). eNOS inactivation by O-GlcNAcylation at the same site was showed. Consequently ED as well, is a disease where dysfunctional GlcNAcylation seems to have an emerging role. The relation between protein O-GlcNAcylation and O-phosphorylation may influence the stress response pathway; cellular levels of O-GlcNAc, regulated by O-GlcNActransferase (OGT) and O-β-NAcetylGlucosaminidase (OGA), are considered as OS sensor and are implicated in the aetiology of various diseases. Human erythrocytes (RBC) are considered as useful model for investigating physiopathological conditions and someglycohydrolases and OGA, present on RBC plasma membrane and cytosol, have been proposed as new, early and sensitive oxidative stress markers. Methods. To compare the oxidative status of 27 ED patients (36.1±8 years) and 30 matched controls (34.1±7 years), plasma antioxidant total defences (Lag-time, determined by measuring kinetics of Cu-stimulated plasma peroxidation), OGA, cytosolic and membrane Hexosaminidase (Hex-c, Hex) and α-D-Glucosidase (αGLU) activities (by fluorimetric assay) were evaluated. Results. Compared to controls, ED patients plasma membrane Hex and αGLU activities were significantly higher (p<0.01); Lagtime values (p<0.01), Hex-c and OGA activities (p<0.001) were significantly lower. Conclusions. Data clearly confirmed: the strong OS in ED patients; the role of OGA and others considered enzymes as early OS biomarkers and suggest, indirectly, a possible alteration of O-GlcNAcylation pattern of erythrocytic proteins.