Long-term Effects (3 months) of Aerobic Treadmill Exercise and Rosemary Extract (100 mg/kg) on Hippocampal Neurodegeneration of Old Male Rats

Aging is a phenomenon that, with a sequence of time-dependent changes, causes neurodegeneration and decreases the physiological function of the brain. Oxidative stress is one of the effective mechanisms in the neurodegeneration and aging process of the nervous system. Since the antioxidant effects of aerobic exercise and rosemary extract have been shown separately and mostly in the short term. In this study, we investigated the long-term effects of aerobic exercise and rosemary oral extract, separately and together, on the rate of the hippocampal neurodegeneration in old male rats.

Animals were treated for three months (5 days per week) with treadmill aerobic exercise and daily (once a day) oral administration (gavage) of 100 mg/kg rosemary extract (containing 40% carnosic acid). The number of intact and degenerated neurons in the hippocampus were counted by Nissl and fluorescence Fluoro-jade B staining methods, respectively.

The mean number of intact neurons in the CA1 region of the hippocampus showed significant increase in the exercise, exercise-rosemary (p<0.001) and rosemary (p<0.05) groups compared to the control groups (intact and vehicle). The number of degenerated neurons stained showed a significant decrease in the animals in exercise, rosemary and exercise-rosemary groups (p<0.001) compared to the control groups (intact and vehicle).

Aerobic exercise and consumption of rosemary extract (containing 40% carnosic acid) for three months, individually and in combination, were able to maintain neuronal density in the CA1 region of the hippocampus in old rats. Also, data analysis showed that long-term regular aerobic exercise had a stronger protective effect on maintaining hippocampal cell density than rosemary extract.