Volumetric changes in the aging rat brain and its impact on cognitive and locomotor functions

Abstract

Impairments in cognitive and locomotor functions usually occur with advanced age, as do changes in brain volume. This study was conducted to assess changes in brain volume, cognitive and locomotor functions, and oxidative stress levels in middle- to late-aged rats. Forty-four male Sprague-Dawley rats were divided into four groups: 14, 18, 23, and 27months of age. H magnetic resonance imaging (MRI) was performed using a 7.0-Tesla MR scanner system. The volumes of the lateral ventricles, medial prefrontal cortex (mPFC), hippocampus, striatum, cerebellum, and whole brain were measured. Open field, object recognition, and Morris water maze tests were conducted to assess cognitive and locomotor functions. Blood was taken for measurements of malondialdehyde (MDA), protein carbonyl content, and antioxidant enzyme activity. The lateral ventricle volumes were larger, whereas the mPFC, hippocampus, and striatum volumes were smaller in 27-month-old rats than in 14-month-old rats. In behavioral tasks, the 27-month-old rats showed less exploratory activity and poorer spatial learning and memory than did the 14-month-old rats. Biochemical measurements likewise showed increased MDA and lower glutathione peroxidase (GPx) activity in the 27-month-old rats. In conclusion, age-related increases in oxidative stress, impairment in cognitive and locomotor functions, and changes in brain volume were observed, with the most marked impairments observed in later age.

Age-related changes of malondialdehyde, body weight and organ weight in male mice

“…At the age of 48 weeks a two-fold increase in MDA concentrations was found as compared with both the ages of 12 and 24 weeks. The results of this study showing increased MDA concentrations with aging are apparently similar to the results of the study by Hamezah et al, (19) which showed increased MDA concentrations and decreased glutathione peroxidase (GPx) concentrations in older rats (27 weeks). The linear increase in MDA concentration started in 18-to 27-week old rats.…”

“…Similar to the increase in brain ventricular volume, the volume of the cerebellum apparently also increases with age. (19) Apparently both of these caused the increases in brain weight in this study.…”

“…(13)(14)(15) In experimental animals, studies on changes in organ mass are aimed at determining the agerelated developmental pattern of an organ and also the underlying mechanism of the aging process. (16)(17)(18)(19) Therefore, studies on experimental animals are far more feasible to be performed by investigators as compared with studies on humans.…”

“…(18) The brain experiences a rapid increase in volume at the age of less than 20 weeks and thereafter the development becomes static. (19) In humans, there is a negative correlation between aging and the weight of the brain, kidneys, liver, and spleen. (14) On the other hand, a positive correlation is found between aging and morphological changes of the heart.…”

Mitochondrial Dysfunction as a Key Event during Aging: From Synaptic Failure to Memory Loss

“…During normal aging, it is well established that there is a reduction in the surface area and cortical thickness, resulting in a volume loss in the whole brain, being the non-cortical regions, such as the hippocampus and striatum, more vulnerable to this age-related atrophy [111]. In this context, a study performed with Sprague-Dawley rats of 14, 18, 23, and 27 months of age showed changes in the volume of different brain parts using magnetic resonance imaging (MRI) [112]. In that study they showed enlargement of lateral ventricles and a decrease in the volume of the medial prefrontal cortex, hippocampus, and striatum in 27-month-old rats, which correlates with cognitive deficiency.…”