The oral administration of D-galactose induces abnormalities within the mitochondrial respiratory chain in the brain of rats.

D-Galactose (D-gal) chronic administration via intraperitoneal and subcutaneous routes has been used as a model of aging and Alzheimer disease in rodents. Intraperitoneal and subcutaneous administration of D-gal causes memory impairments, a reduction in the neurogenesis of adult mice, an increase in the levels of the amyloid precursor protein and oxidative damage; However, the effects of oral D-gal remain unclear. The aim of this study was to evaluate whether the oral administration of D-gal induces abnormalities within the mitochondrial respiratory chain of rats. Male Wistar rats (4 months old) received D-gal (100 mg/kg v.o.), during the 1st, 2nd, 4th, 6th or 8th weeks by oral gavage. The activity of the mitochondrial respiratory chain complexes was measured in the 1st, 2nd, 4th, 6th and 8th weeks after the administration of D-gal. The activity of the respiratory chain complex I was found to have increased in the prefrontal cortex and hippocampus in the 1st, 6th and 8th weeks, while the activity of the respiratory chain complex II increased in the 1st, 2nd, 4th, 6th and 8th weeks within the hippocampus and in the 2nd, 4th, 6th and 8th weeks within the prefrontal cortex. The activity of complex II-III increased within the prefrontal cortex and hippocampus in each week of oral D-gal treatment. The activity of complex IV increased within the prefrontal cortex and hippocampus in the 1st, 2nd, 6th and 8th weeks of treatment. After 4 weeks of treatment the activity increased only in hippocampus. In conclusion, the present study showed that the oral administration of D-gal increased the activity of the mitochondrial respiratory chain complexes I, II, II-III and IV in the prefrontal cortex and hippocampus. Furthermore, the administration of D-gal via the oral route seems to cause the alterations in the mitochondrial respiratory complexes observed in brain neurodegeneration.