Voluntary exercise and estrogen replacement ameliorate the impairment of fear memory and decrease in the number of neurons in the hippocampus induced by ovariectomy in rats

Previous studies indicated that the exercise has beneficial effects on cognitive activities and ovariectomies causes the impairment of learning and memory. The aim of this study was to determine the influence of voluntary exercise and estrogen replacement on the effects of ovariectomy on fear memory and hippocampal neuron number in rat.
In this experimental study, adult female Wistar rat (180-220 gr) were used. One week after ovariectomy, the rats received ß-Stradiol (estrogen 20 µg/kg) or vehicle (2ml/kg) daily and were allowed to freely exercise in a running wheel for 2 weeks. After this period, their learning and memory were trained and tested on a passive avoidance task that succeeded by a retention test two days later. Then, all animal were decapitated, and their hippocampi were removed. The number of neurons was counted in different regions of hippocampus.
Analysis of data indicated that the ovariectomy impaired the fear memory and decreased the number of neurons in the hippocmpaus. Volunatry exercise or exstrogen replacement alone, and together improved the deficits in fear memory and neuron counting induced by ovariectomy
Voluntary exercise and estrogen have benfical effects on cognitive deficits associated with the reduction of female sex hormones such as seen in post-monpouse woman.