Neuroprotective Effects Of Genistein On Dopaminergic Neurons In Vitro

Part One the Effects of Genistein on the Expression of Dopaminergic Neurons and Synaptophysins in a MPP⁺ Parkinson's Disease ModelObjective To study the effects of genistein on the espression of dopaminegic neurons and synaptophysin. Methods The neurons obtained from ventral mesencephalon of E14-16 SD rat were cultured and divided into four groups with different mediums: the control group only containing 10% fetal bovine serum (FBS) in culture medium, MPP⁺group (injured by 1-methyl-4-phenylpyridium ion(MPP⁺) besides containing 10% FBS in culture medium),E₂+MPP⁺group (E₂+MPP⁺+10% FBS) and GST+MPP⁺group(GST+MPP⁺+10% FBS). The cultured neurons were stained with immunoflorescence by using tyrosine hydroxylase (TH) and synaptophysin (SYN) antibodies to observe the morphology and the development of TH positive neurons and the expression of synaptophsins, using microtubule-associated protein (MAP-2) antibody to study the extent of injured neurons. Using methyl thiazolyl tetrazolium (MTT) to assay the cell viability and metabolism state. Results The number of the TH positive neurons and the SYN imrmmoreactive products in MPP⁺group were low in comparison with those in control group, E₂+MPP⁺ group and GST+MPP⁺group (P＜0.05). The cell viability was also low in MPP⁺group and the content of MAP-2 reduced obviously in MPP⁺ group. No significant difference were observed between control group, E₂+MPP⁺group and GST+MPP⁺ group. Conclusions Genistein has neuroprotective effect similar to estrogen on dapaminergic neurons in vitro.Part Two the Effcets of Genistein on the Expression of Dopaminergic Neurons and Bax Protein after blocking the Estrogen Receptor (ER) by Tamoxifen in a MPP⁺ Parkinson's Disease ModelObjective To observe the effects of genistein on the expression of dopaminegic neurons and Bax protein after tamoxifen blocked the estrogen receptor(ER). Methods The neurons obtained from ventral mesencephalon of E14-16 SD rat were cultured and divided into four groups with different mediums: the control group only containing 10% fetal bovine serum (FBS) in culture medium, MPP⁺group (injured by 1-methyl-4-phenylpyridium ion(MPP⁺) besides containing 10%FBS in culture medium). GST+MPP⁺group (GST+MPP⁺+10% FBS) and TAM+GST+MPP⁺group (TAM+GST+MPP⁺+10% FBS). The cultured neurons were stained with immunocytochemistry by using tyrosine hydroxylase (TH) antibody to observe the morphology and the development of TH positive neurons. Using methyl thiazolyl tetrazolium (MTT) to assay the cell viability and metabolism state. The expression of Bax protein was examined by using Western Blot. Results The number of the TH positive neurons in TAM+GST+MPP⁺group was low in comparison with those in control group and GST+MPP⁺group. The cell viability in TAM+GST+MPP⁺group was low in comparison with those in control group and GST+MPP⁺group. The expression of Bax protein in TAM+GST+MPP⁺group was higher than that in control group and GST+MPP⁺group. The significant difference between MPP⁺group and other three groups were found in the number of the TH positive neurons, the cell viability and the expression of Bax protein. Conclusions TAM has the partial effect of down regulation of the protective effect of GST on dopaminergic neurons. The neuroprotective effect of GST on dopaminergic neurons was not only by combining with ER but also by other pathway in vitro; the expression of Bax protein was high in injured neurons, indicating that Bax protein has an important effect on the apoptosis of the dopaminergic neurons.