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Met-enkephalin modulation of age-related changes in red cell antioxidant status
S Sobocanec1, T Balog, V Sverko
1Division of Molecular Medicine, Rudjer Bosković Institute, Bijenicka 54, 10000 Zagreb, Croatia.
Abstract:
Opioid peptides have been recognized as modulators of reactive oxygen species (ROS) in mouse macrophages and human neutrophils. Since the effect cannot be ascribed to its direct scavenger properties, in this study, we tested the hypothesis that methionine-enkephalin (MENK) modulates ROS by alteration of antioxidant enzyme activity (AOE). For this purpose superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) are measured in red blood cells of 1, 4, 10, and 18-month-old CBA mice of both sexes injected with 10 mg/kg MENK. The results indicate that MENK-affected antioxidant enzyme activity of red blood cells is age- but not sex-related. The most abundant effects were observed at the reproductive stage. Increased sensitivity to oxidative stress by opioid peptides was in both sexes mainly due to increased SOD activity followed by GPX decrease. Thus, the damage ascribed to opioid peptides might be, at least partly, ascribed to deleterious effects of accumulated hydrogen peroxide (H2O2).
Insights
Methionine-enkephalin (MENK) alters antioxidant enzyme activity in mouse red blood cells, impacting oxidative stress responses. This effect is age-dependent, not sex-dependent, with significant changes observed during the reproductive stage.
Area of Science:
- Biochemistry
- Immunology
- Neuroscience
Background:
- Opioid peptides, like methionine-enkephalin (MENK), are known modulators of reactive oxygen species (ROS).
- The mechanism by which MENK influences ROS is not fully understood and is unlikely due to direct scavenger properties.
Purpose of the Study:
- To investigate the hypothesis that MENK modulates ROS by altering antioxidant enzyme activity (AOE).
- To examine the age- and sex-related effects of MENK on AOE in mouse red blood cells.
Main Methods:
- Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities were measured.
- Red blood cells from CBA mice of varying ages (1, 4, 10, 18 months) and both sexes were analyzed after MENK injection (10 mg/kg).
Main Results:
- MENK significantly affected AOE in red blood cells in an age-dependent, but not sex-dependent, manner.
- The most pronounced effects were observed during the reproductive stage.
- Increased sensitivity to oxidative stress was primarily linked to elevated SOD activity and decreased GPX activity.
Conclusions:
- MENK modulates antioxidant enzyme activity in mouse red blood cells, influencing oxidative stress.
- The observed age-related changes suggest a role for MENK in age-associated oxidative stress.
- Potential deleterious effects of opioid peptides may stem from accumulated hydrogen peroxide (H2O2) due to altered enzyme activity.
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