Inhibition of microRNA-200a Upregulates the Expression of
Striatal Dopamine Receptor D2 to Repress Apoptosis of Striatum via the cAMP/PKA Signaling Pathway in Rats with Parkinson's Disease.
Cell Physiol Biochem 2018;
51:1600-1615. [PMID:
30497067 DOI:
10.1159/000495649]
[Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 11/21/2018] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS
Parkinson's disease (PD) is a neurodegenerative movement disease with a high annual incidence. Accumulating evidence demonstrates that microRNAs play important roles in the pathogenesis of multiple neurological disorders, including PD. This study aims to investigate how microRNA-200a (miR-200a) regulates striatal dopamine receptor D2 (DRD2) to affect apoptosis of striatum in rats with PD and to explore the associated mechanism.
METHODS
After successfully establishing a PD model by 6-hydroxydopamine injections, PD rats were mainly treated with miR-200a mimics, inhibitors, Forskolin or a combination of miR-200a inhibitors and Forskolin. High-performance liquid chromatography-electrochemical detection (HPLC-ECD) was employed to detect the levels of dopamine, 3, 4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and chemistry colorimetric methods were applied to detect the levels of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). A TUNEL assay and immunocytochemical staining were performed to observe apoptosis and tyrosine hydroxylase (TH)-positive cells in the striatum. The expression of miR-200a, DRD2, Bad, Bax, Bcl-2, cAMP and PKA was determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot assays.
RESULTS
In the cellular experiments, after transfection with the inhibitor of miR-200a, decreased levels of Bax, GSH-Px, SOD, dopamine, DOPAC and HVA but increased levels of MDA and Bcl-2 were found along with a reduced apoptosis rate and increased TH-positive cell number. In addition, downregulating miR-200a resulted in lower expression of AKT, cAMP and PKA but higher expression of DRD2 and CREB, indicating that the downregulation of miR-200a increases DRD2 expression, which blocks the cAMP/PKA signaling pathway.
CONCLUSION
This study provides evidence that the inhibition of miR-200a can repress apoptosis in the striatum via inhibition of the cAMP/PKA signaling pathway by upregulating DRD2 expression in PD rats.
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