Physiological oxidative stress model: Syrian hamster Harderian gland - Sexdifferences in antioxidant enzymes

The Syrian hamster Harderian gland, a juxtaorbital organ exhibiting marked gender-associated differences in contents of porphyrins and melatonin, was used as a model system for comparing strong tin females) and moderate tin m ales) physiologoical oxidative stress. Histological differences showing muc h higher cell damage in females were studied in conjunction with lipid pero xidation and activities of superoxide dismutase, catalase, glutathione pero xidase, and glutathione reductase. Lipid peroxidation and enzyme activities were measured throughout the circadian cycle, revealing the importance of dynamical processes in oxidative stress. Especially in lipid peroxidation a nd in catalase, short-lasting rises exhibited strongest gender differences. Peaks of lipid peroxidation were about three times higher in females, comp ared to males. Catalase peaks of females exceeded those in males by several hundred-fold. Average levels of superoxide dismutase and glutathione perox idase were about three or two times higher in females, respectively. A clea r-cut diurnally peaking rhythm was found in glutathione peroxidase of femal es, which was not apparent in males. Glutathione reductase showed differenc es in time patterns, but less in average activities. The time courses of li pid peroxidation and of protective enzymes are not explained by circulating melatonin, whereas melatonin formed in the Harderian gland should contribu te to differences in average levels. Neither damage nor antioxidative defen se simply reflect the illumination cycle and are, therefore, not only a con sequence of photoreactions. (C) 2001 Elsevier Science Inc.