GM1 Alleviates Parkinson’s Disease By Regulating Autophagy Pathway And Removing The Aggregated α-synuclein

Background and Objectives:Parkinson’s Disease(PD) is the second popular neurodegenerative disease among the middle-aged and the old. The main pathological features are lesions of dopaminergic neuronal cells in the substantia nigra pars compacta and the lewy bodies in the neurons. Damage on dopaminergic neuronal cells provide the clues in diagnosis and treatment of PD patients. To date, the medications on PD all aim at restoring the level of the specific neurotransmitter, dopamine, including monoamine oxidase B(MAOB) inhibitor, dopamine receptor activator and anticholinergic agent, to name just a few, however, these chemicals are not radical cures. On the other hand, removal of lewy bodies and degradation of its key contents, aggregated α-synuclein, are becoming promising targets on treatment of PD, but this field is yet on experimental stage and not totally clear now. It has been suggested that α-synuclein can not only regulate the recycle of synaptic vesicle but also play a role in the release of dopamine, besides, it can also have an influence on the activity of Tyrosine hydroxylase(TH) which is an essential enzyme in synthesis of dopamine. Thus the removal of α-synuclein is a potential approach in cure of PD.Monosialotetrahexosylganglioside(GM1) is a medication used in clinial treatment on PD and other neural diseases. Both experiments on animals and data from clinic are evidence for its nice effects on PD. It can help recover the damaged neurons and injured synapses and axon, but the exact molecular mechnism remains unclear. Our topic want to explore the answer for this question. Methods:(1) GM1 pharmacodynamic evaluation on MPTP treated mice and an innitial assessment on its relation with autophagyC57BL/6 mice were used as the experimental subjects, and they were grouped as follows: control, MPTP, GM1 high dose(GM1-H), MPTP+GM1 low dose(MPTP+GM1-L), MPTP+GM1 high dose(MPTP+GM1-H), MPTP+GM1-H+3-MA and MPTP+Sele. Mice, except for control and GM1-H groups, were administrated with MPTP at a dose of 30 mg/kg/d, intraperitoneal injection(i.p.), for 5 days. After this, mice were given certain dose of GM1, 3-MA and Sele accordingly while control and MPTP groups were treated with normal saline. The methods of adiministration of GM1 and 3-MA are both i.p., and there were two dose of GM1, 25 mg/kg/d and 50 mg/kg/d, respectively and 3-MA was 15 mg/kg/d which was adminidtraed 30 mins before GM1. In terms of Sele, the approach was intragastric administration, with a dose at 60 mg/kg/d. Pole-climbing test, rotarod test and Cat Walk system were used to evalue the behaviour of mouse once the administration was over.(2) Exploration on mechanism of protective effects of GM1 on PD injuryThe active metabolite of MPTP, MPP+, was used to cause a damage on SH-SY5 Y cells and this work as a PD celluar model. First, exposed cells with a rang of different dosage of MPP+, and then chose the dosage that caused a inhibitory ratio of 50%, and this condition was 1 m M for 36 h. Then distinct dosage of GM1 were added when the damage process was over(removal of culture media with MPP+ and added the media with GM1), and we observed the inhibition ratio. Next, we observed the morphologic changes of cells exposed to MPP+ only or MPP+ and GM1. Using Western Blot assay, we evalued levels of proteins like TH, α-synuclein and autophagy indicator LC3. Meanwhile, we utilised the transfected plasmid to mark LC3 and to see the autophagy flux. Later, we observed the colocalization of LC3 which is the symbol of autophagosome and α-synuclein under confocal microscopy. Results:(1) Mice behavior experiments data showed a huge difference between control and MPTP groups whereas the Sele could reverse these changes in all these three kinds of tests. Moreover, MPTP+GM1-L and MPTP+GM1-H groups provided data that indicated a recover on mice behavior compared with MPTP group. MPTP+GM1-H+3-MA treated mice had a bad motor ability compared with MPTP+GM1-H, however, GM1-H showed good data that is silimilar to control group.(2) Celluar experiments results described a protective effect of GM1 on MPP+ treated SH-SY5 Y cells, and we could saw cells in MPP+ group had a lot of vacuoles inside the cell and these cells seemed a little longer with less synapsis. But when GM1 were added these morphologic changes could be compromised. Western Blot assays indicated that GM1 could increase level of TH and decrease amount of α-synuclein. Interestingly, GM1 caused a rise in turnover of LC3 I to LC3 II compared with autophagic activator and autopahgic inhibitor, which implied that GM1 could launch autopahgy process. A further data on evaluation of impacts of GM1 on autophagy could also be an evidence, these data were obtained from Weatern Blot and confocal microscopy approaches. Also, we found that the colocalization of LC3 and α-synuclein saw a rising trend when exposed GM1 with different hours. Conlusion:Data from mice experiments described that GM1 could relieve the injury that was caused by MPTP; celluar results showed that GM1 could trigger autopahgy process through which the accumulated α-synuclein could be removed and thus played a protective effect on MPP+ treated SH-SY5 Y cells.