Protective Effect Of Estrogen On Substantia Nigral Neuron In Rats Parkinson's Disease Model

In addition to influencing the modulation of nerve system on reproductive and nonreproductive behaviors, estrogen acts on the central nervous system to protect nervious neurons. At present, it is proved that Estrogen plays a role in protecting neurons in hippocampus area, cerebellum cortex etc. However, it is not clear that whether estrogen can protect nigral dopaminergic neurons, to what extent it's protecting role and whether it's protecting role in nigral dopaminergic neurons is of great importance in clinic.Parkinson's disease is a disease caused by death or dysfunction of dopaminergic neurons and its incidence varies greatly between the male and the the female. The incidence ratio of men to women is 1.7-3.5:1. The relation between estrogen amount decrease and incidence ratio of old women has been paid more attention in the world. Now it was reported that estrogen can increase the dopamine amount in substantia nigra of female rats Parkinson's disease Model. But there are not direct evidence to approve the role of estrogen protecting the nigral dopaminergic neurons. For this reason, we observed the neuroprotective effects of estrogen on nigral dopaminergic neurons by immunity histochemistry way as following three sections.Section oneProtective Effect of Estrogen on Substantia NigralNeuron in Female Rats OvariectomizedThirty healthy firty grade female wistar rats (weighing 200-300g) were provided by the animal center of the fourth military medical university. They were assigned into two groups at random with fifteen rats in each group. In group one, 10ug estradiol was administered twice a day in each rat after ovariectomy. In group two,10ug sesame oil was given twice a day in each rat after ovariectomy. All rats received alternative illumination in twenty hours and were fed to their content freely. In a week, 8ug 6-hydroxydopamine was injected into right side substantia nigra of rat by stereotaxic opertion according to the rat brain stereotaxic atlas of Bao Xin-min. After thirty days, the rats received subcutaneous injection of apomorphine(0.5mg/kg) to provoke rotation. The number of rotation was counted and wrote down. Then all rats narcotized were perfused through the left heart ventricles with paraformaldehyde and phosphate buffered saline with 5g/L glutaraldehyde. One hour later the integral brain was taken out and then fixed for four hours. The brains were put into100g/L saccharose buffer at 4°C over a night. On the next day continuous sections of 25um thickness were made in cryostat box. The section made began from anterior horn of lateral ventricle. One in every five sections was taken in the portion from corpus luysi to the disappearance of substantia nigra for nissl staining and TH antiserum(dilution 1:2000) immunohistochemic staining respectively. The TH positive cells were counted in substantianigra of each section with image processing system. And the mean number of TH positive neurons on both sides in each mesencephaion section was calculated. The number of rotations provoked by apomorphine of group one was obviously less than that of group two. However, the number of TH positive neurons was more than that of group two. Thus we come to the conclusion that estrogen can protect the nigral dopaminergic neurons from apoptosis caused by 6-hydroxydopamine.Section twoProtective Effect of Estrogen of Different Dose onSubstantia Nigral Neuron in Female Rats of ParkinsonDiseaseFourty healthy firty grade female wistar rats (weighing 200-300g) were assigned into four groups at random with ten rats in each group. Group one was the normal control. In group two, three and four all rats were ovariectomyed. Then in group two, 5ug estradiol was administered twice a day in each rat. In group three,10ug estradiol was given twice a day in each rat after ovariectomy. In group four, 20ug estradiol twice a day in each rat. All rats received alternative illumination in twenty hours and were fed to their food freely. In a week, 8ug 6-hydroxydopamine was injected into right side substantia nigra of rat by stereotaxic opertion according to the rat brain stereotaxic atlas of Bao Xin-min. Mean time the amount of estrogen in rat blood was measured. After thirty days, the rats received subcutaneous injection of apomorphine(0.5mg/kg) to provoke rotation. The number of rotation was counted and wrote down.Then all rats narcotized were perfused through the left heart ventricles with paraformaldehyde and phosphate buffered saline with 5g/L glutaraldehyde. One hour later, the integral brain was taken out and then fixed for four hours. The brains were put into 100g/L saccharose buffer at 4°C over a night. On the next day, continuous sections of 25um thickness were made in cryostat box. The section made began from anterior horn of lateral ventricle. One in every five sections was taken in the portion from corpus luysi to the disappearance of substantia nigra for nissl staining and TH antiserum(dilution 1:2000) immunohistochemic staining respectively. The TH positive cells were counted in substantia nigra of each section with image processing system. And the mean number of TH positive neurons on both sides in each mesencephalon section was calculated. In the group with estrogen under natural level, the number of the TH positive cells of rats are much less compared with those groups with natural level estrogen ( P<0.01). Natural level estrogen play more important role in protecting the substantia nigral dopaminergic neuron of femal rats than those under natural level. However, estrogen over the natural level have equal effect to the naturallevel one. Section threeEffect of Tamoxifen on The Estrogen to Protect SubstantiaNigral NeuronsThirty healthy firty grade female wistar rats (weighing 200-300g) were provided by the animal center of the fourth military medical university. They were assigned into three groups at random with ten rats in each group. In group one, 10ug estradiol was administered twice a...