The Effects of Soy Milk on Histomorphometric Changes of Olfactory Bulb in Neonatal Ovariectomized RatsSprague- Dawley strain

Background & Objective: Soy milk contains isoflavones that comprises the phytoestrogens families. They have structural similarities with mammalian estrogen. This study was done to investigate the effects of soy milk on histomorphometric changes of olfactory bulb in neonatal ovariectomized rats.   Materials & Methods: Thirty female rats Sprague- Dawley strain (one-day old) were kept in a standard laboratory condition. Afterwards, they were randomly divided into six groups with 5rats (a control, a sham and four experimental groups). The ovaries of one-week old experimental groups were removed by surgery. In experimental groups of 2,3and 4, the rats received soy milk twice a day from the 14th day to the end of 2 month 0.75, 1.5 and 3 ml/kg respectively by gavage. At the end of two month and after anesthesia and blood sampling to measure estrogen hormone, the olfactory bulb of all rats to investigate the thickness of layers and the number of cells in different layers of olfactory bulb histomorphometric was divided. Finally the results were analyzed through One-way variance and Tukey Test considering p<0.05.   Results: According to this study, the following results were  obtained. Low estrogen level due to ovariectomized infant rats has reduced the thickness of external granular layer. Mitral cell layer and internal plexiform layer as well as cell number in most layers of the olfactory bulb through feeding high level of soy milk to ovariectomized infants leading to high serum concentrations of 17-β estradiol that subsequently increased thickness and cell numbers of olfactory bulb. Conclusions: The soy milk can be used as a source of synthetic hormone replacement.