An investigation of the effects of exercise on hippocampal function in young, middle-aged and aged rats

Abstract

The hippocampus is a brain structure that is important for higher cognitive functions, possesses a high degree of plasticity, and is particularly vulnerable to the aging process (Burke & Barnes, 2006). Symptoms of hippocampal dysfunction and cognitive alteration are seen with both severe cognitive decline such as that associated with Alzheimer’s disease and other forms of dementia (Small et al, 1999). Given that demographic trends suggest the elderly population is increasing (Miller & O’Callaghan, 2005), it is especially important that interventions with the potential to improve cognitive function or ameliorate neurodegenerative decline are thoroughly investigated. Research has shown that in addition to improving general health and being associated with numerous benefits to the cardiovascular system, exercise positively affects neuronal function and has the capacity to improve cognitive function. Thus, exercise may be viewed as a simple means of maintaining brain function and promoting brain plasticity (Cotman & Berchtold, 2002). It is well-recognized that neurotrophins, most prominently brain-derived neurotrophic factor (BDNF), are central to the exercise-induced effects on brain function. Although research in this area is extensive, the precise mechanisms that underlie an exercise-induced improvement in cognitive function have yet to be identified. The main aims of this research were to investigate the effects of exercise on hippocampal function in young, middle-aged and aged rodent populations, and to compare the effects of acute and chronic exercise protocols on cognitive function. In addition, the cellular modifications mediating an exercise-effect within the brain were explored.