Effects of pramipexole on the Circadian Rhythm Dyfunction In a 6-Hydroxydopamine Treated Model of Parkinson's disease

• 1、Institute of Neuroscience,Soochow University,Suzhou,Jiangsu Province,215123

Abstract：Objective: To investigate the effect of different doses of pramipexole (PPX) on the circadian dysfunction in Parkinson's disease（PD） model. Methods: In vitro, dopaminergic cell line（PC12 cell） was treated with 6-Hydroxydopa (6-OHDA) and PPX.Real-time quantitative polymerase chain reaction (Q-PCR) was used to detect mRNA level of clock gene at different time points. The rat model was constructed by bilateral striatal with 6-OHDA lesion. 6-OHDA rat model was injected with saline or PPX for 14 days. Rotarod test and footprint test were used to assess motor function. Animal tissues like striatum, suprachiasmatic nucleus (SCN) and liver were collected at 6:00, 12:00, 18:00 and 24:00 for test. Western Blot were used to detect the protein expression of Tyrosine hydroxylase(TH). Q-PCR were used to detect the alterations of the clock gene mRNA level. And high performance liquid chromatography (HPLC) was used to measure the neurotransmitters content in the striatum. Analysis of variance was used for data analysis. Results：In vitro, after 6-OHDA treatment on PC12 cells, the mRNA level of the clock gene at ZT12 was decreased, and the expression of the clock gene was restored to the level of the control group after PPX treatment. Animal experiments showed that the motor deficits in PD rats were rescued by low dose of PPX treatment, and high dose ofPPX exacerbated the motor deficits. Western Blot showed that TH expression was decreased in 6-OHDA group, butPPX had no effect. Q-PCR showed that high dose of PPX caused abnormality of Bmal1in SCN ; low dose of PPX restored abnormal Rorα mRNA level in 6-OHDA group, and high dose PPX aggravated abnormally. In liver, low dose of PPX rescued clock gene expression abnormality caused by 6-OHDA treatment, but high dose of PPX exacerbated the abnormality. Dopamine (DA) and 5-HT significantly reduced in 6-OHDA lesion group compared with the sham group. DA and 5-HT reduction recovered after PPX treatment. Conclusion：The circadian dysfunction of clock gene expression was confirmed in PD model. Treatment with low dose of PPX (0.1 mg/kg) can rescue circadian dysfunction in PD, but high dose of PPX (1 mg/kg) may aggravate circadian dysfunction. This study aimed to explore the effects of PPX on the circadian dysfunction of PD models.

Keywords： Neurobiology Parkinson's Disease Circadian rhythm Pramipexole Circadian Clock genes 6-Hydroxydopamine