| Gonadal steroid hormone, especially estrogen, exerted considerable effects upon the pituitary, hypothalamus, nigrostriatal and mesolimbic dopaminergic (DAergic) systems, of which, amygdala (Amy) was one of the most important site affected by estrogen and the main projection site for DAergic neurons from midbrain. Amy appeared obvious pathologic changes during the process of parkinson's disease (PD) caused by dysfunction of DAergic neurons, which resulted in special syndromes occurring in partial patients of PD. Our previous experiments showed that exogenous estrogen could promote dopamine (DA) release from Amy of ovariectomized (OVX) rats. In the present study, in order to investigate the effects of endogenous estrogen on the DAergic terminals in Amy and the DAergic neurons in midbrain, fast cyclic voltammetry (FCV) was used to examine DA release evoked by electrical stimulation from Amy of female rats in different phases of estrus cycle, OVX rats and male rats. And tyrosine hydroxylase (TH) immunohistochemistry was employed to measure the numbers of DAergic neurons of ventral tegmental area (VTA) and substantia nigra (SNc) in the rats. In addition, DA release from Amy of female, male and OVX rats was monitored after intracerebroventricular (i.c.v) injection of estrogen-like medicine, effective contraction of WuJiBaiFengWan and soy isoflavones, to detect the influence of the drugs on the DAergic systems of midbrain in the rats. Furthermore, in order to examine the effects of sulfated polysaccharides from brown seaweeds GS201 on the DAergic neurons of midbrain, DA release was measured from striatum(Str) following electrical stimulation of medial forebrain bundle (MFB) and from Amy following electricalstimulation of VTA in the model rats of PD. The results were as follows:l.DA release evoked by electric stimulation of VTA from Amy of male rats was significantly lower compared with female and OVX rats. Amy DA release of proestrus female rats was apparently higher than estrus, metestrus and ciestrus female rats, but no significant difference was observed among estrus, metestrus and ciestrus female rats. DA release in OVX rats was higher compared with male rats, but lower than proestrus female rats. No difference appeared among OVX rats and estrus, moiestrus, ciestrus female rats .2.The numbers of the TH immunoreactive neurons in VTA of male rats were apparently less than female and OVX rats, and no significant difference appeared between female and OVX rats.S.There was no difference among the numbers of the TH immunoreactive neurons in SNc of female, OVX and male rats.4.DA release from Amy of female and OVX rats increased as early as 5min after i.c.v injection of effective contraction of WuJiBaiFengWan at doses of 300 u g/ml, 600 U g/ml 2.5 u 1 respectively and returned to the level of control rats within 40min. There was a dose-dependent relationship between DA release and the administered dosage of the drug. But the drug has showed no influence on DA release from Amy of male rats in 60min after injection.5.DA release from Amy of female and OVX rats significantly increased in 5min after i.c.v injection of soy isoflavones at a dosage of 66.7 u g/kg and declined to the control level within 20min. However, the drug was ineffective on male rats during 30min after injection.6.Sulfated polysaccharides from brown seaweeds GS201 injected by Img/d intraperitoneally for 7 days could promote DA release from lesioned side of striatum in rats, but not from unlesioned side compared with NS treated rats .7.Also, DA release from lesioned side but not unlesioned side of Amy in rats increased after injection of GS201 for 7 days compared with NS treated rats .In summary, the results suggested that DA release from Amy was modulated by different serum level of estrogen in female, OVX and male rats. The numbers of the DAergic neurons hi VTA of midbrain showed significant sex differece. WuJiBaiFengWan and soy isoflavones as natural estrogen-like medicine could increase DA release from Amy and exert estrog...
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