| It has been well-known that gonadal steroid hormones, estrogen especially, plays an important role in protecting the brain from neurodegenerative processes, including Parkinson's disease (PD). Estrogen, but not androgen, has been reported to prevent l-Methyl-4-phenyl-l,2,3,6-tetrahydropyridine(MPTP)-induced dopamine (DA) depletion. Phytoestrogen and Chinese medicine, as well as acupuncturing without the use of any drug have also been demonstrated to have neuroprotective effects in PD. As a well-known gynaecological tonic in China, Bak Foong Pill (BFP, also known as Bai Feng Wan) has long been recognized to have estrogen-like activities, has also been reported to exert beneficial effects on various functional systems including central nervous system. For exploring possible neuroprotective effect of BFP extracts and estrogen, and related mechanism(s) underlying the actions, we observed the actions of BFP extracts on tyrosine hydroxylase (TH) gene expression in the midbrain of ovariectomized (OVX) and normal female mice. TH and dopamine transporter (DAT) mRNA levels in the striatum, midbrain, cortex and cerebellum have been detected in BFP extracts- and estrogen-pretreated PD model mice. Effects of BFP extracts on DAT and TH gene expressions have also been measured in both female and male PD mice. In addition, we compared the effects of BFP extracts and estrogen by observing the 1176 mouse cDNAs using microarray technique. The mechanisms underlying the effects of BFP extracts have been detected by measuring the pro-apoptotic gene-Bax expression by employing RT-PCR and observing the apoptotic cells by using flow cytometry. In vivo DA release from the central amygdaloid nucleus have also been measured with fast cyclic voltammetry (FCV). Results were as follows:1. TH mRNA levels are significantly higher in the MPTP-induced female PD model mice with/without BFP extracts pretreatment (3g/kg, 2 weeks), compared with OVX female mice.2. In the OVX C57BL/6 mice, MPTP significantly decreased DAT and TH mRNA levels in the striatum, midbrain and cerebellum, but not the cortex of the mice (p<0.001). However, MPTP-challenge with BFP extracts pretreatment demdnstrated reduced neurotoxicity, with DAT and TH mRNA levels either not affected by MPTP or affected to a significantly lesser extent in the midbrain and striatum as compared to the MPTP treated controls. 17B-estradiol treatment prevented MPTP-induced reduction of DAT expression in striatum and midbrain, but failed to alter TH expression.3. MPTP significantly decreased TH and DAT mRNA levels in the striatum and midbrain of both female and male C57BL/6 mice. While, MPTP challenge with BFP extracts pretreatment showed reduced neurotoxicity, with TH and DAT mRNA levels in the midbrain and striatum higher than that of the vehicle treated animals.4. To explore anti-apoptotic action of BFP extracts, we measured the expression level of Bax, a pro-apoptotic gene, in a dopamine-secreting neuroendocrine cell line, PC 12, by semi-quantitative RT-PCR. The results showed that Bax mRNA level was significantly increased by MPTP administration (1000 for 24 h). BFP extracts (1000 ug/ml) pretreatment for 6 h attenuated MPTP-elevated expression level of Bax.5. Furthermore, we measure apoptotic cell population in PC 12 cells by propidium iodide (PI) staining with flow cytometry. The number of apoptotic cells was greatlyenhanced by MPTP, an averaged 11.8% of apoptotic cells as compared to 0.8 % in the control. However, PC 12 cells grew in the medium containing BFP significantly reduced the MPTP-induced apoptotic cell population, with only an averaged 5.3 % of apoptotic cells observed.6. Among the 1176 mouse cDNAs, 40 genes expression changed in the midbrain and hypothalamus of PD model mice fed with BFP extracts, and 93 individual genes were regulated significantly in the mice injected with 17B -estradiol, by employing the microarray technique. Noteworthy, 35 genes were the same as the BFP-treated group.7. Intracerebroventricular...
|
PDF Full Text Request