ABSTRACT
Parkinson's disease (PD) is a multifactorial disorder of the nervous system where a progressive loss of dopaminergic neurons exist. However, the pathogenesis of PD remains undefined, which becomes the main limitation for the development of clinical PD treatment. Demethylenetetrahydroberberine (DMTHB) is a novel derivative of natural product berberine. This study was aimed to explore the neuroprotective effects and pharmacological mechanism of DMTHB on Parkinson's disease using C57BL/6 mice. A PD model of mice was induced by administration of MPTP (20 mg·kg-1) and probenecid (200 mg·kg-1) twice per week for five weeks. The mice were administered with DMTHB daily by gavage at the dose of 5 and 50 mg·kg-1 for one- week prophylactic treatment and five-week theraputic treatment. The therapeutic effects of DMTHB were evaluated by behavior tests (the open field, rotarod and pole tests), immunohistochemical staining of tyrosine hydroxylase (TH), Nissl staining and biochemical assays. The molecular mechanisms of DMTHB on the key biomarkers of PD pathological states were analyzed by Western blot (WB) and qRT-PCR. DMTHB treatment alleviated the behavioral disorder induced by MPTP-probenecid. Nissl staining and TH staining showed that the damage of dopaminergic neurons in the substantia nigra was remarkably suppressed by DMTHB treatment. Western blot results showed that the ratio of Bcl-2/Bax and TH increased, but the level of α-synuclein (α-syn) was remarkably reduced, which indicated that the apoptosis of dopaminergic neurons in mice was significantly reduced. The protein phosphorylation of p-PI3K, p-AKT and p-mTOR also increased about 2-fold, compared with the model group. Furthermore, qRT-PCR results demonstrated that the mRNA levels of pro-inflammatory cytokines, IL-1β and TNF-α, were reduced, but the level of anti-inflammatory cytokine IL-10 increased after DMTHB treatment. Finally, the cellular assay displayed that DMTHB was also a strong antioxidant to protect neuron cell line PC12 by scavenging ROS. In this study, we demonstrated DMTHB alleviates the behavioral disorder and protects dopaminergic neurons through multiple-target effects includubg anti-apoptotic, anti-inflammatory and antioxidant effects.
Subject(s)
Animals , Mice , Dopaminergic Neurons/pathology , Mice, Inbred C57BL , Parkinson Disease/pathology , Parkinsonian Disorders/chemically induced , Substantia NigraABSTRACT
<p><b>BACKGROUND</b>Vascular smooth muscle cell (VSMC) proliferation following arterial injury plays a critical role in a variety of vascular proliferative disorders, such as atherosclerosis and restenosis after balloon angioplasty. Herpes simplex virus-thymidine kinase (HSV-TK)/ganciclovir (GCV) and E. coli cytosine deaminase (CD)/5-fluorocytosine (5-Fc) suicide gene systems have been successfully employed in cardiovascular gene therapy, respectively. We reasoned that coexpression of both HSV-TK with CD suicide genes would lead to increased cell killing. To test this imagine, the adenoviral vectors expressing TK and/or CD genes were developed and tested on vascular smooth muscle cells.</p><p><b>METHODS</b>Adenoviral vectors, including Ad-EF1alpha-CD-cytomegalovirus (CMV)-TK coexpressing both CD and TK double suicide genes, Ad-EF1alpha-CD and Ad-CMV-TK expressing CD and TK respectively, and control vector Ad-CMV-LacZ, were constructed and prepared with homologous recombination in RecA + E. coli cells. Integration and expression of CD and/or TK gene were identified by PCR and Western blot. Primary cultured VSMCs were infected at a multiplicity of infection (MOI) of 20 with exposure to their matching prodrugs 5-Fc and GCV. Cell mortality was measured by methyl thiazolyl tetrazolium (MTT) assays. Flow cytometry analysis was used to detect cell death. Apoptotic cells were analyzed using Hoechst 33342 fluorescence dye as a DNA probe. Genomic DNA cleavage of apoptotic VSMCs was tested by agarose gel electrophoresis.</p><p><b>RESULTS</b>Recombinant adenovirus expressing CD and/or TK suicide genes were successfully constructed. Both single and double suicide genes could be integrated into adenoviral genome and expressed. Cytotoxic effects of Ad-EF1alpha-CD-CMV-TK double suicide genes combined with 5-Fc and GCV were higher than those of Ad-CMV-TK and Ad-EF1alpha-CD single gene groups. The rate of cell survival was only (9 +/- 3)% in the Ad-EF1alpha-CD-CMV-TK group, but (37 +/- 3)% in the Ad-CMV-TK and (46 +/- 4)% in the Ad-EF1alpha-CD groups (P < 0.05). Flow cytometry analysis indicated that the killing mechanisms of the groups were different. Necrosis and apoptosis were involved in the mechanism of the double gene group. Based on the DNA stainability with Hoechst 33342, the apoptotic rates of VSMCs in the Ad-EF1alpha-CD-CMV-TK [(11.0 +/- 2.1)%] and Ad-CMV-TK [(12.0 +/- 2.2)%] groups were higher than those in Ad-CMV-LacZ [(1.2 +/- 0.11)%] and Ad-EF1alpha-CD [(5.0 +/- 1.8)%] groups (P < 0.05, respectively). DNA smear could be observed in both Ad-CMV-TK and Ad-EF1alpha-CD-CMV-TK groups after administration of prodrugs.</p><p><b>CONCLUSIONS</b>The killing effect on rat VSMCs mediated by adenoviral CD/TK double suicide genes is superior to that of single suicide gene. The killing mechanism of recombinant adenovirus coexpressing CD/TK double suicide genes is mainly through cytotoxic effect and apoptosis.</p>