Behavioral Assessment and Blood Oxidative Status of Aging Sprague Dawley Rats through a Longitudinal Analysis

Cognitive frailty emerges as one of the threats to healthy aging. It is in continuum with advancing of age with uncertain indicator between pathological and physiological changes. Alterations in pathways associated with the aging process have been observed including oxidative stress, lipid metabolism, and inflammation. However, the exact mechanisms leading to cognitive decline are still unclear.

This study was sought to assess the level of cognitive functions and linked with blood oxidative status during normal aging in rats.

A longitudinal study using male Sprague Dawley rats was performed starting from the age of 14 months old to 27 months old. Cognitive functions tests such as open field, Morris water maze and object recognition were determined at the age of 14, 18, 23, and 27 months old and were compared with group 3 months old. Blood was collected from the orbital venous sinus and oxidative status was determined by measuring the level of DNA damage, lipid peroxidation, protein oxidation and antioxidant enzymes activity.

Aged rats showed declining exploratory behavior and increased in the level of anxiety as compared to the young rats. The level of DNA damage increased with increasing age. Interestingly, our study found that both levels of malondialdehyde and plasma carbonyl content decreased with age. In addition, the level of superoxide dismutase activity was significantly decreased with age whereas catalase activity was significantly increased from 18 months of age. However, no significant difference was found in glutathione peroxidase activity among all age groups.

The progressions of cognitive impairment in normal aging rats are linked to the increment in the level of DNA damage.