Effects of 17-β estradiol on neurogenesis in the hippocampus of ovariectomized mice

Background & Aims: Adult neurogenesis occurs in the two main areas of the brain of most mammalian species in; sub ventricular zone, and the dentate gyrus of the hippocampus. Many factors such as 17-β estradiol affect neurogenesis in the hippocampus. The aim of this study was to investigate the effect of exogenous 17-β estradiol on neurogenesis in the ovariectomized (OVX) mice. Materials & Methods: NMRI mice were divided into five experimental groups: 1- Sham, 2- Control, 3- Treated with single dose of 17-β estradiol two weeks after ovariectomy and euthanized 24 hours later, 4- Treated with single dose of 17-β estradiol two weeks after OVX and euthanized 48 hours later, 5- Treated with single dose of Sesame Oil (vehicle) 2 weeks after OVX and euthanized after 24 hours. Animals were perfused transcardially with paraformaldehyde. Brains were removed and its sections for cresyl fast violet staining and Glial fibrillary acidic protein (GFAP) and BrdU immunohistochemistry were prepared. Cells were counted and investigated using light and fluorescent microscopy. Results: Neuronal density and Proliferation of hippocampal progenitor cells in the CA1 region of 17-β estradiol -treated mice were significantly increased up to 24 hours. The density of astrocytes in different region of the hippocampus was significantly increased after treatment by 17-β estradiol. Conclusion: Cell shape and density of hippocampal CA1 neurons are influenced by 17-β estradiol. In addition, density and morphology of glial cells, especially astrocytes in different regions of the hippocampus are affected by 17-β estradiol. Thus, 17-β estradiol can improve neurogenesis in the CA1 region of the hippocampus.