The Influence Of Different Antiparkinsonian Drugs On Dopaminergic System And The Effect Of Pergolide And L-dopa On PC12 Cells

Parkinson's disease is a neurodegenerative disease, pathologically characterized by the degeneration of nigrostriatal dopaminergic neurons, resulting in the reduction of dopamine in striatum. The process of this disorder is chronic progressive. Despite L-dopa is the most efficacious drug for symptom reversal in the current therapies in PD, there is concern that most patients develop levodopa-related complications with long-term treatment, such as dyskinesia, motor fluctuations and decline in effect-tiveness. Several in vitro studies have demonstrated that dopamine is toxic to dopaminergic neurons mediated by producing apoptosis in the cluture. However, whether L-dopa is definite toxic is still in dispute. Recent research have focused on the treatment of slowing the progression of disease and having the neuroprotective effect in PD. In vitro results suggest that dopamine agonists may have the potential neuroprotective effect because of the properties of antioxidation and scavenging radical oxygen. In recent research, neuroimaging is proved to provide an objective method of evaluating the progression of PD and be used to monitor the the striatl dopaminergic degeneration with different treatment. Because of lack of placebo group in the previous studies, it is difficult to conclude that dopamine agonists have the effect of neuroprotection and L-dopa may accelerate the progression of the disease.In this study, we select patients with early PD who were double-blinded randomly prescribed with different antiparkinsonian drugs to assess the dopaminergic degeneration using ^99mTc-TRODAT-1 SPECT imaging dopamine transporter and ¹³¹I-epidepride SPECT imaging dopamine D₂ receptor. In the experimental study, we pretreated PC12 cells with pergolide or L-dopa in different concentration before adding MPP⁺, to observe the change of viability of cells; to assay the the change of level of cellular tyrosine hydroxylase(TH) protein;to evaluate the change of apoptoticcells. Based on the results, we can investigate the influence of pergolide and L-dopa on the impairment of PC12 cells induced by MPP+.Part IThe influence of different antiparkinsonian drugs on dopaminergic system in basal ganglionAim: To assess the dopaminergic degeneration after initial treatment with different medication within 14 months in early PD using "Tc-TRODAT-l SPECT imaging dopamine transporter and ulI-epidepride SPECT imaging dopamine D2 receptor.Method: Seventy-two patients with early PD (Hoehn&Yahr I—11 stage) were enrolled and assigned to four groups using a double-blind, randomized method. They were randomly prescribed with antane (6mg/d) (n=15) , madopa 250' ( L-dopa 500mg/d) (n=22) , L-deprenyl (selegiline 7. 5mg/d) (n=22) and dopamine agonist (pergolide 0. 5mg/d) (n=13) within 14 months. Patients underwent "Tc-TRODAT-l SPECT imaging dopamine transporter and '"i-epidepride SPECT imaging dopamine D2 receptor at baseline, subsequently while on therapy (7months) and after 14 months follow-up. And at the same time, clinical scores were recorded using the Unified Parkinson's Disease Rating Scale (UPDRS). Result:1. The clinical scores had the trend of elevation in the antane group and the selegiline group compared with the baseline, the latter showed the significant difference suggesting the acceleration of symptoms and signs. The clinical scores had the trend of decline in the madopa group and the dopamine agonist group compared with the baseline, the former showed the significant difference suggesting the amelioration of symptoms and signs.2. 99mTc- TRODAT-1 SPECT imaging results (scans 3) showed significant decline in striatal DAT level (P<0. 05) in the antane group and the madopa group compared with the baseline. But in the selegiline group and the dopamine agonist group , no significant decrease was found in striatal DAT level (P>0. 05) . The loss of ""Tc-TRODAT-l uptake in basal ganglionwas significantly reduced only in the dopamine agonist group compared with the control group(antane)(P<0. 05).3. l!1I-epidepride SPECT imaging results (scans 2and 3) showed no significant difference in dopamine Dj receptor level compared with the baseline and no significant difference was found within the groups.Part II The effect of pergolide and L-dopa on PC12 cells in vitroAim: In the experimental studies, we treated PC12 cells with pergolide and L-dopa at different concentrations, to investigate the influence of them on the impairment of PC12 cells induced by MPP+. Method: We pretreated PC12 cells with pergolide or L-dopa at different concentrations before adding MPP+, to observe the change of viability of cells;to assay the the change of level of cellular tyrosine hydroxylase(TH) protein;to evaluate the change of apoptotic cells. Result:1. The results showed that pergolide promote the growth of PC12 cells and increase the cell viability at low concentrations(0. OOlumol/L and 0. Olumol/L). The cell viability showed a trend of gradual decline with the gradual increase of the concentration. L-dopa inhibit the growth of PC12 cells and decrease the cell viability at relatively high concentrations (^ 100ujnol/L).2. The results showed that pergolide increase the cell viability following the impairment of MPP* at low concentrations(0.01 umol/L), suggesting its partial protection of PC12 cells against MPP toxicity. When treated with L-dopa, the cell viability was increased at low concentrations(0. lumol/L) following the impairment of MPP, which showed a trend of gradual decline with the gradual increase of the concentration. And the injury of PC12 cells was aggravated when treated with L-dopa+MPP* at high concentrations(1000umol/L).3. The levels of TH protein were upregulated when treated with pergolide at low concentrations(0. OOlumol/L). The levels of TH protein were downregulated when treated with L-dopa at relatively high...