Background： Parkinson＇s disease （PD） patients with long-term levodopa （L-DOPA） treatment are suffering from severe circadian dysfunction. However, it is hard to distinguish that the circadian disturbance in pati...Background： Parkinson＇s disease （PD） patients with long-term levodopa （L-DOPA） treatment are suffering from severe circadian dysfunction. However, it is hard to distinguish that the circadian disturbance in patients is due to the disease progression itself, or is affected by L-DOPA replacement therapy. This study was to investigate the role of L-DOPA on the circadian dysfunction in a rat model of PD. Methods： The rat model of PD was constructed by a bilateral striatal injection with 6-hydroxydopamine （6-OHDA）, followed by administration of saline or 25 mg/kg L-DOPA for 21 consecutive days. Rotarod test, footprint test, and open-field test were carried out to evaluate the motor function. Striatum, suprachiasmatic nucleus （SCN）, liver, and plasma were collected at 6：00, 12：00, 18：00, and 24：00. Quantitative real-time polymerase chain reaction was used to examine the expression of clock genes. Enzyme-linked immunosorbent assay was used to determine the secretion level of cortisol and melatonin. High-performance liquid chromatography was used to measure the neurotransmitters. Analysis of variance was used for data analysis. Results： L-DOPA alleviated the motor deficits induced by 6-OHDA lesions in the footprint and open-field test （P 〈 0.01, P 〈 0.001, respectively）. After L-DOPA treatment, Bmall decreased in the SCN compared with 6-OHDA group at 12：00 （P 〈 0.01） and 24：00 （P 〈 0.001 ）. In the striatum, the expression ofBmall, Rorα was lower than that in the 6-OHDA group at 18：00 （P 〈 0.05） and L-DOPA seemed to delay the peak of Per2 to 24：00. In liver, L-DOPA did not affect the rhythmicity and expression of these clock genes （P 〉 0.05）. In addition, the cortisol secretion was increased （P 〉 0.05）, but melatonin was further inhibited after L-DOPA treatment at 6：00 （P 〈 0.01）. Conclusions： In the circadian system of advanced PD rat models, circadian dysfunction is not only contributed by the degeneration of the disease itself but also long-term L-DOPA therapy may further aggravate it.展开更多
基金This work was supported by grants from the National Natural Science Foundation of China （No. 91649114）,Jiangsu Provincial Special Program of Medical Science （No. BL2014042）, the Plans for Graduate Research and Innovation in Colleges and Universities of Jiangsu Province （No. KYZZ15_0334）, and Suzhou Clinical Research Center of Neurological Disease （No. Szzx201503）. This was also partly supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions and Jiangsu Provincial Medical Key Discipline Project.
文摘Background： Parkinson＇s disease （PD） patients with long-term levodopa （L-DOPA） treatment are suffering from severe circadian dysfunction. However, it is hard to distinguish that the circadian disturbance in patients is due to the disease progression itself, or is affected by L-DOPA replacement therapy. This study was to investigate the role of L-DOPA on the circadian dysfunction in a rat model of PD. Methods： The rat model of PD was constructed by a bilateral striatal injection with 6-hydroxydopamine （6-OHDA）, followed by administration of saline or 25 mg/kg L-DOPA for 21 consecutive days. Rotarod test, footprint test, and open-field test were carried out to evaluate the motor function. Striatum, suprachiasmatic nucleus （SCN）, liver, and plasma were collected at 6：00, 12：00, 18：00, and 24：00. Quantitative real-time polymerase chain reaction was used to examine the expression of clock genes. Enzyme-linked immunosorbent assay was used to determine the secretion level of cortisol and melatonin. High-performance liquid chromatography was used to measure the neurotransmitters. Analysis of variance was used for data analysis. Results： L-DOPA alleviated the motor deficits induced by 6-OHDA lesions in the footprint and open-field test （P 〈 0.01, P 〈 0.001, respectively）. After L-DOPA treatment, Bmall decreased in the SCN compared with 6-OHDA group at 12：00 （P 〈 0.01） and 24：00 （P 〈 0.001 ）. In the striatum, the expression ofBmall, Rorα was lower than that in the 6-OHDA group at 18：00 （P 〈 0.05） and L-DOPA seemed to delay the peak of Per2 to 24：00. In liver, L-DOPA did not affect the rhythmicity and expression of these clock genes （P 〉 0.05）. In addition, the cortisol secretion was increased （P 〉 0.05）, but melatonin was further inhibited after L-DOPA treatment at 6：00 （P 〈 0.01）. Conclusions： In the circadian system of advanced PD rat models, circadian dysfunction is not only contributed by the degeneration of the disease itself but also long-term L-DOPA therapy may further aggravate it.
