The influence of gender, age and treatment time on brain oxidative stress and memory impairment induced by d-galactose in mice

Chronic exposure to d-galactose (d-gal) serves as a model for age-related oxidative damage and cognitive dysfunction. However, methods used, including the dose and treatment time of d-gal as well as the gender, age and strain of animals used, vary greatly among published articles. In this study, we investigate the effect of gender, age and treatment time on brain oxidative stress and spatial memory deficits induced by d-gal in mice, respectively. Eight-week-old female mice injected with 100 mg/kg d-gal per day, for 6 weeks, did not show spatial memory impairment or high levels of hydroxyl radical, protein carbonyl and malondialdehyde in brain homogenates, although brain reactive oxygen species were increased when compared with saline control mice. In contrast, both 8-week-old male mice and 24-week-old female mice receiving 100 mg/kg d-gal for 6 weeks, or 8-week-old female mice receiving 100 mg/kg d-gal for 10 weeks showed spatial memory deficits and significant increases in the above oxidative markers, compared with their corresponding controls. These results demonstrate that d-gal-induced brain oxidative stress and spatial memory impairment are dependent upon exposure time of d-gal, plus gender and age of the animals used. The findings can serve as a useful guide for successfully establishing d-gal induced age-related oxidative damage models.