BACKGROUND: Studies have shown that estrogen receptor alpha (ERα), nerve growth factor(NGF), interleukin-2 (IL-2), and androgen receptor (AR) expression in the cerebellum decreaseswhen estrogen levels decrease in vivo. Soybean isoflavone, a type of non-steroid estrogen withsimilar molecular structure and function to estradiol, exhibits estrogen-like characteristics.OBJECTIVE: To investigate the effects of various doses of soybean isoflavone on expression ofERα, NGF, IL-2, and AR in the cerebellum of ovariectomized rat, and to determine whether there is adose-dependent effect.DESIGN, TIME AND SETTING: Controlled trial at the cellular and molecular level. The study wasperformed at the Experimental Animal Engineering Center, College of Veterinary Medicine, SichuanAgricultural University from July 2006 to May 2008.MATERIALS: Soybean isoflavone, comprised of daidzin, genistein and isoflavone, was provided byTaiyuan Yuantai Biochemical Industry, China. The ERα, NGF, IL-2, and AR in situ hybridization kit,rabbit anti-rat ERα, NGF, IL-2, and AR monoclonal antibodies, and SABC kit were purchased fromWuhan Boster Biological Technology, China.METHODS: A total of 50 female, Sprague Dawley rats, aged 3 months, were randomly assigned to5 groups, with 10 animals in each group. With the exception of the sham-operation group (abdominalcavity opening alone), all rats underwent bilateral ovariectomy. At 14 days after surgery, rats in thehigh-, middle-, and low-dose soybean isoflavone groups were subcutaneously injected with 1.5, 1.0,and 0.5 mg/kg soybean isoflavone, respectively, every 2 days for 6 consecutive weeks. Rats in thesham-operation and ovariectomized groups were subcutaneously injected with absolute alcohol(0.5 mL/kg).MAIN OUTCOME MEASURES: Expression levels and distribution of ERα, NGF, IL-2, and AR in thecerebellum were detected by immunohistochemistry and in situ hybridization.RESULTS: Compared with the sham-operation group, immunoreactive products and hybridizationsignals of ERα, NGF, IL-2, and AR were significantly decreased in the cerebellar cortex and nuclei ofovariectomized rats (P< 0.05 or P< 0.01), but increased following soybean isoflavone treatment. Inparticular, levels of the high-dose soybean isoflavone group were almost restored to levels of thesham-operation group (P > 0.05). The immunoreactive products were primarily located in thecytoplasm and neurites, and rarely in the cell membrane and nuclei. However, the hybridizationsignals were predominantly located in the nuclei, but rarely in the cytoplasm, cell membrane, orneurites.CONCLUSION: Soybean isofiavone upregulated ERα, NGF, IL-2, and AR protein and geneexpression in a dose-dependent manner, and played an important role in sustaining and protectingstructure and function of cerebellar neurons. Moreover, the similarity of expression patterns of thesemolecules indicated that they were mutually interactive during the regulation of soybean isoflavoneto the cerebellum. BACKGROUND: Studies have shown that estrogen receptor alpha (ERα), nerve growth factor (NGF), interleukin-2 (IL-2), and androgen receptor (AR) expression in the cerebellum arewhen estrogen levels decrease in vivo. Soybean isoflavone, a Type of non-steroid estrogen withsimilar molecular structure and function to estradiol, exhibits estrogen-like characteristics.OBJECTIVE: To investigate the effects of various doses of soybean isoflavone on expression ofERα, NGF, IL-2, and AR in the cerebellum of ovariectomized rat , and to determine whether there is adose-dependent effect.DESIGN, TIME AND SETTING: Controlled trial at the cellular and molecular level. The study wasperformed at the Experimental Animal Engineering Center, College of Veterinary Medicine, SichuanAgricultural University from July 2006 to May 2008 .MATERIALS: Soybean isoflavone, comprised of daidzin, genistein and isoflavone, was provided byTaiyuan Yuantai Biochemical Industry, China. The ERα, NGF, IL-2, and AR in situ h The ybridization kit, rabbit anti-rat ERα, NGF, IL-2, and AR monoclonal antibodies, and SABC kit were purchased from Wuhan Boster Biological Technology, China. METHODS: A total of 50 female, Sprague Dawley rats, aged 3 months, were randomly selected Assigned to5 groups, with 10 animals in each group. With the exception of the sham-operation group (abdominalcavity opening alone), all rats underwent bilateral ovariectomy. At 14 days after surgery, rats in thehigh-, middle-, and low-dose Soybean isoflavone groups were subcutaneously injected with 1.5, 1.0, and 0.5 mg/kg soybean isoflavone, respectively, every 2 days for 6 consecutive weeks. Rats in thesham-operation and ovariectomized groups were subcutaneously injected with absolute alcohol(0.5 mL/kg). MAIN OUTCOME MEASURES: Expression levels and distribution of ERα, NGF, IL-2, and AR in the corerebellum were detected by immunohistochemistry and in situ hybridization.RESULTS: Compared with the sham-operation group, immunoreactive products and hybridization SignAls of ERα, NGF, IL-2, and AR were significantly decreased in the cerebellar cortex and nuclei ofovariectomized rats (P<0.05 or P<0.01), but increased following isoflavone treatment. Inparticular, levels of the high-dose soybean isoflavone The group were almost restored to levels of thesham-operation group (P > 0.05). The immunoreactive products were located in the cytoplasm and neurites, and rarely in the cell membrane and nuclei. However, the hybridizationsignals were predominantly located in the nuclei, but rarely In the cytoplasm, cell membrane, orneurites.CONCLUSION: Soybean isofiavone upregulated ERα, NGF, IL-2, and AR protein and gene expression in a dose-dependent manner, and played an important role in sustaining and protecting structure and function of cerebellar neurons. , the similarity of expression patterns of thesemolecules indicated that they were promised during the regulation of soybean isoflavoneto the cerebellum.