| Parkinson’s disease(PD) is a common neurodegenerative disease affecting the older quality of life, and the morbidity is very high in the older people. Its main pathological feature is the degenerating death of dopaminergic neurons in substantia nigra compacta, and the clinical symptoms are resting tremor, muscle rigidity, bradykinesia, and postural instability and so on. Currently, the researches suggested that several fators were associated with the occurrence of PD, such as mitochondrial dysfunction, nerve inflammation, oxidative stress, environmental toxins, genetic mutations, but the exact pathogenesis is unclear. More and more evidences showed that mitochondrial dysfunction and oxidative stress played vital role in the process of the occurrence and development of PD. A lot of free radicals were generated with the mitochondrial dysfunction, the accumulation of free radicals to a certain extent which will cause the mitochondria damage, leading to cell death. For the treatment of PD, levodopa and selegiline and other drugs to alleviate the symptoms were used in clinical, commonly. But these drugs can’t prevent the degenerating of the dopaminergic neurons, and the therapeutic effect became lower with the development of the disease which induced the complications, for instance movement disorders, trembling intensively, unstable. Therefore, m the mitochondria will be a potential drug-target for prophylaxis and treatment of PD, with protecting mitochondria function, inhibiting free radicals generation, preventing mitochondria damage,and so on.In recent year, a nuclear transcription coactivator Peroxisome proliferator-activated receptor γ coactivator of 1a(PGC-1a) was discovered, which played a crucial role in a variety of physiological activity, and became the hot area of research in various fields. The study found that the expression of PGC-1a was reduced in the substantia nigra of Parkinson’s patients and PGC-1a could participate in mitochondrial biogenesis and metabolism, improve cell antioxidant capacity. Pioglitazone as thiazolidinediones TZDs insulin sensitizers can be administered orally and enter into the blood brain barrier, which was used therapy Ⅱdiabetes in clinic. Whether peroxisome proliferator-activated receptor γ(PPARγ) agonists pioglitazone can regulate the expression of PGC-1a, protecting dopaminergic neurons damaged by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP),and improving the symptoms of PD, the question is a subject worthy of further study.The PD model of C57BL/6 mice reproduced with MPTP is a common animal model for studying the pathogenesis and therapies of PD. In the present study, we adopted the animal model, and gave the PGC-1a agonist pioglitazone intervention intragastrically before intraperitoneal injection of MPTP to explore whether pioglitazone could reduce MPTP-induced dopaminergic neurons damage in the substantia nigra of midbrain by regulating the expression of PGC-1a, and relieving symptom of PD in mice. Behavioral tests, immunofluorescence, FJC staining, Western Blot, transmission electron microscopy methods were used in this study.The experimental results are as follows:1. The PD animal model were successfully replicated by intraperitoneal injection of MPTP(30 mg/kg.bw).2. We detected the flexibility and movement coordination of mice by independent active number of times, swimming, rolling bar. The results showed that there were no difference in behavior tests among only using low, medium and high dose of pioglitazone groups and the normal control group. The numbers of stand reduced, the pause time prolonged in the process of swimming, and stayed less time on the rolling bar after MPTP-damaged. And the behaviors were improved after different dose of pioglitazone intervention.3. Immunofluorescence was used to observe the change of TH, PGC-1a and GFAP expression in substantia nigra. The results showed that there were no difference in TH, PGC-1a and GFAP expression among only using low, medium and high dose of pioglitazone groups compared with the normal control group. But the TH, PGC-1a positive cells were reduced after MPTP- damaged, and there were statistical difference in MPTP and low dose pioglitazone intervention group compared with the normal control group(P<0.05). Pioglitazone intervention made TH, PGC-1a positive cells increased(P<0.05), and they had no difference among medium and high dose of pioglitazone intervention groups and the normal control group(P>0.05). GFAP immunofluorescence staining results showed that astrocytes were significantly activated, and the IOD density increased after MPTP-damaged, there were significant difference between with the normal control group and any other groups(P<0.05); IOD values in MPTP group and low dose intervention group were the highest,but IOD values decreased in the medium and high dose intervention groups, with the dose increasing the IOD dropped lower.4. FJC apoptotic cells displayed only in the substantia nigra in the MPTP group, the other groups were not seen.5. Western Blot was used to detect the protein changes of PGC-1a, TH. The results showed that TH and PGC-1a protein levels increased than MPTP group after pioglitazone intervention. There were no significant difference among medium, high dose of intervention groups and the normal control group(P>0.05).6. The TEM was used to observe the ultrastructure and mitochondria numbers in the substantia nigra compacta in each group. The results suggested that there were a lot of mitochondria around the nucleus in the normal control group, and there were no swelling phenomemon and the morphology of mitochondria were more fuller, mitochondrial cristae were seen obviously. While in MPTP group there were almost no mitochondria exist around the nucleus, and the nuclei were shrinking with severe demyelinating phenomenon. The number of mitochondria around the nucleus and ultrastructure had a certain degree of improvement after pioglitazone intervention, and the effect was the best in intervention group among the three intervention grops.We can draw the conclusions through analyze the above results, the conclusions are as follows:1. There were no effects on the mice behavior, the degenerating of dopaminergic neurons in substantia nigra and the activity of astrocytes only use pioglitazone intervention.2. Pioglitazone could improve the locomotor activity, swimming, the balance on the rolling bar of Parkinson’s disease mice, increase the number of dopaminergic neurons’ survival, and inhibiting nerve inflammation by inhibiting the activation of GFAP.3. Pioglitazone could ameliorate the ultrastructure and the number of mitochondria in substantia nigra dopaminergic neurons, and could reduce inflammation, to protect the dopaminergic neurons in PD mice by increasing PGC-1a.These results indicated that pioglitazone could reduce the death or apoptosis of dopaminergic neurons, improve the symptoms of PD by resistancing to oxidative stress and anti-inflammatory effects. This study can provide a basis research data for pioglitazone to become an alternative drug for prevention and treatment of PD. |
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