Erythrocyte membrane alterations during ageing affect β-D-glucuronidase and neutral sialidase in elderly healthy subjects

In this study, a comparison between elderly (> 70 years) and young subjects reveals that elder people are subject to a higher oxidative stress, which causes an increase in plasma hydroperoxide levels (18%) and a decrease in antioxidant defenses (25%). Moreover, the marked decrease of the erythrocyte membrane fluidity observed in elderly subjects was likely to affect the behaviour of some membrane glycohydrolases. In fact, a significant decrease of beta-D-glucuronidase and neutral sialidase (30 and 50%, respectively) was detected. Activity differences were also observed when erythrocytes were further distinguished according to their biological age. Striking differences between young and elderly subjects were observed for beta-D-glucuronidase and neutral sialidase in young and senescent erythrocytes, respectively. Overall beta-D-glucuronidase decreases with the subjects' age, while neutral sialidase levels are higher in the elderly. This is presumably due to the localization of these enzymes in distinct plasma membrane micro-domains, which are differently peroxidized. A possible role of these enzymes in signaling praecox membrane alterations has also been evidenced. (c) 2004 Elsevier Inc. All rights reserved.