Effect of Different Doses of Soy Isoflavones on Spatial Learning and Memory in Ovariectomized Rats

Several studies indicate that estrogen use increase performance on some tests of cognition especially in postmenopausal women. These steroids have many side effects, thus, other estrogenic agents with fewer side effects are needed to develop alternative treatment strategies. The main objection of this study was to evaluate the effects of different doses of dietary soy meals (with or without isoflavone) on spatial learning and memory in ovariectomized (OVX) rats. Female Wistar rats with the exception of intact group were ovariectomized at the first line of study. Subjects were divided into six groups. The control group rats (c) were gonadally intact, while the others were OVX. OVX groups received normal diet (0), treated with 10 gr soy (10), 20 gr soy (20), 10 gr isoflavone free soy (-10) or 20 gr isoflavone free soy (-20) in daily diet for four weeks. The spatial learning and memory were tested using Morris water maze. Rats were trained in water maze to find a hidden escape Platform. Rats received 6 blocks that each block consisted of 3 trials. Following acquisition trials, one probe trial were conducted in which the platform was removed. Soy meal diet (with or without isoflavone) in ovariectomized rats caused improvement of performance across 18 trials of Acquisition. Our results suggest that soy consumption apart from containing isoflavone or not is a potential alternative to estrogen in the improvement of cognition.