Background: The decline in estrogen level after menopause results in a decrease in life quality and different neurological disorders such as memory impairment. However, hormone replacement therapy remains controversial. Some studies have been investigated the effects of soy phytoestrogens (e.g. genistein) on cognitive brain functions. This study aimed to examine the effect of oral administration of soy extract on the apoptosis of hippocampus cells.

Materials and Methods: In this study, 30 rats were randomly allocated into 3 equal groups: 1) Sham (surgery without ovariectomy) 2) ovariectomized (OVX) and 3) treatment (OVX+soy extract). The animals in the treatment group received soy extract (60mg/kg) daily in drinking water by gavage for six weeks. At the end of treatment, brain samples of all animals were collected for tissue sectioning. Apoptosis in hippocampal cell was studied using the TUNEL method and a light microscopy.

Results: Oral administration of soy extract significantly decreased the number of apoptotic (neuronal and glial) cells (P<0.05), while ovariectomy significantly increased the number of apoptotic cells in the ovariectomized group compared to the Sham (P=0.034) and treatment groups (P=0.016).

Conclusion: Results of this study indicate that the oral administration of soy extract in ovariectomized rats had neuroprotective effects by decreasing the number of apoptotic cells.