Integrated PET/MRI With 11C-CFT and 18F-FDG for levodopa response difference in Parkinson's disease.

AIM: Parkinson's disease is one of the most common neurodegenerative diseases. Excellent levodopa responsiveness has been proposed as a characteristic supporting feature in substantiating the PD diagnosis. However, a small portion of clinically established PD patients shows poor levodopa response. This study aims to investigate brain function alterations of PD patients with poor levodopa responsiveness by PET/MRI. METHOD: A total of 46 PD patients were recruited. They all completed 11C-CFT PET/MRI scans and the acute levodopa challenge test. Among these 46 PD patients, 42 participants further underwent 18F-FDG PET/MRI scans. Clinical variables regarding demographic data, disease features and cognition scales were also collected. Based on the improvement rate of UPDRS-III, PD patients were divided into non-responders (improvement rate < 33 %) and responders (improvement rate ≥ 33 %). Statistical parametric zapping was performed to analyze molecular imaging. Dopaminergic uptake and metabolism of 70 brain regions were converted to quantitative values and expressed as standard uptake value (SUV). SUV was further normalized by the cerebellum. The resulting SUV ratios and clinical variables were then compared by SPSS. RESULTS: The difference between levodopa non-responders (n = 17) and responders (n = 29) in the UPDRS III baseline was statistically significant and the former had a lower UPDRS III baseline (19 (10, 32), p＜0.05). In contrast, no statistical difference between these two groups was found in age, gender, disease duration, cognition, motor subtype and Hoehn-Yahr stage. Dopaminergic uptake differences between levodopa non-responders (n = 17) and responders (n = 29) were shown in the left inferior frontal cortex (1.00 ± 0.09 vs 1.07 ± 0.08, p < 0.05 and FDR < 0.2), the right posterior cingulum (1.10 ± 0.10 vs 1.20 ± 0.13, p < 0.05 and FDR < 0.2) and the right insula (1.21 ± 0.12 vs 1.30 ± 0.10, p < 0.05 and FDR < 0.2). The metabolic alterations between levodopa non-responders (n = 16) and responders (n = 26) were shown in the right supplementary motor area (1.30 (1.18, 1.39) vs 1.41 (1.31, 1.53), p < 0.05 and FDR < 0.2), right precuneus (1.37 ± 0.10 vs 1.47 ± 0.18, p < 0.05 and FDR < 0.2), right parietal cortex (1.14 ± 0.15 vs 1.27 ± 0.21, p < 0.05 and FDR < 0.2), right supramarginal gyrus (1.16 (1.12, 1.26) vs 1.25 (1.14, 1.46), p < 0.05 and FDR < 0.2), right postcentral gyrus (1.15 (1.08, 1.32) vs 1.24 (1.17, 1.39), p < 0.05 and FDR < 0.2), medulla (0.75 ± 0.07 vs 0.80 ± 0.07, p < 0.05 and FDR < 0.2), right rolandic operculum (1.25 (1.18, 1.32) vs 1.33 (1.25, 1.50), p < 0.05 and FDR < 0.2), right olfactory (0.95 (0.91, 1.01) vs 1.01 (0.95, 1.15), p < 0.05 and FDR < 0.2), the right insula (1.15 (1.06, 1.22) vs 1.21 (1.12, 1.35), p < 0.05 and FDR < 0.2) and the left cerebellum crus (0.96 (0.91, 1.01) vs 0.92 (0.86, 0.96), p < 0.05 and FDR < 0.2). CONCLUSIONS: PD patients with poor response to levodopa showed less severe impairment of baseline motor symptoms, more severe dopaminergic deficits in the left inferior frontal, right posterior cingulate cortex and the right insula, and lower metabolism in the right supplementary motor area, right precuneus, right parietal cortex, right supramarginal gyrus, right postcentral gyrus, medulla, right rolandic operculum, right olfactory, the right insula and higher metabolism in the left cerebellum crus.

Transcranial Magnetic Stimulation Alleviates Levodopa-Induced Dyskinesia in Parkinson's Disease and the Related Mechanisms: A Mini-Review.

After long-term use of levodopa, Parkinson's patients almost inevitably develop dyskinesia, a kind of drug side effect manifesting as uncontrollable choreic movements and dystonia, which could be crippling yet have limited therapeutic options. Transcranial magnetic stimulation is the most widely studied non-invasive neuromodulation technology to treat levodopa-induced dyskinesia. Many studies have shown that transcranial magnetic stimulation has beneficial effects on levodopa-induced dyskinesia and is patient-tolerable, barely with reported adverse effects. Changes in brain connectivity, neuroplasticity, neurotransmitter, neurorestoration, and blood flow modulation could play crucial roles in the efficacy of transcranial magnetic stimulation for levodopa-induced dyskinesia. The appearance of new modes and application for emerging targets are possible solutions for transcranial magnetic stimulation to achieve sustained efficacy. Since the sample size in all available studies is small, more randomized double-blind controlled studies are needed to elucidate the specific treatment mechanisms and optimize treatment parameters.

Morin exerts neuroprotective actions in Parkinson disease models in vitro and in vivo.

AIM: To investigate the neuroprotective effects of morin on 1-methyl-4-phenylpyridinium ion (MPP(+))-induced apoptosis in neuronal differentiated PC12 cells as well as in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson disease (PD). METHODS: PC12 cells were challenged with MPP(+) in the presence or absence of morin. Cell viability was determined using MTT assay. Cell apoptosis was measured using flow cytometry. Generation of reactive oxygen species (ROS) was assayed using fluorescence assay. In an MPTP mouse model of PD, behavioral deficits, striatal dopamine content, and number of dopaminergic neurons were measured. RESULTS: MPP(+) induced apoptosis and ROS formation in PC12 cells. Concomitant treatment with morin (5-50 mumol/L) significantly attenuated the loss of cell viability and apoptosis when compared with MPP(+) treatment alone. Morin also attenuated ROS formation induced by MPP(+). MPTP induced permanent behavioral deficits and nigrostriatal lesions in mice. When administered prior to MPTP, morin (20 to 100 mg/kg) attenuated behavioral deficits, dopaminergic neuronal death and striatal dopamine depletion in the MPTP mouse model. CONCLUSION: The findings suggest that morin has neuroprotective actions both in vitro and in vivo, and may provide a novel therapeutic agent for the treatment of PD and other neurodegenerative diseases.

[Proteolytic stress induced by environmental toxins in dopaminergic neurons: an experimental study].

OBJECTIVE: To explore the role of proteolytic stress induced by environmental toxins in degeneration and death of dopaminergic neurons. METHODS: Nerve growth factor-treated-rat adrenal pheochromocytoma cells of the line PC12 were co-incubated with 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenylpyridinium ion (MPP(+)), and rotenone for 24 hours. MTT assay was used to measure the cell viability induced by these neurotoxins with different concentrations. The expression levels of alpha-synuclein and ubiquited proteins in every group were observed with laser scanning confocal technique. The enzymatic activities of three main hydrolases in proteasome were measured by detection of the fluorophore of various cleft synthetic fluorogenic peptides. RESULTS: 6-OHDA, MPP(+), and rotenone decreased the activity of PC12 cells dose-dependently. Co-incubated with 100 micromol/L 6-OHDA, 75 micromol/L MPP(+), and 20 nmol/L rotenone, the activity of PC12 cells decreased by 52%, 44%, and 40% respectively. Immunofluorescence double labeling confirmed the overexpression of alpha-synuclein and ubiquitin and pellet accumulation in the cytoplasm induced by three toxins. Compared with those in the control group, the trypsin-like, chymotrypsin-like, and PgH-like activities of proteasome were markedly decreased in the MPP(+) and rotenone groups (all P < 0.05) and slightly decreased in the 6-OHDA 100 micromol/L group (all P > 0.05), but after the exposure to 6-OHDA 200 micromol/L for 24 h, the activities of the three enzymes decreased rapidly, the activities of the three enzymes were 7.2 +/- 0.6, 79.6 +/- 2.7 and 4.2 +/- 0.5 FU/100 microg respectively (vs 13.9 +/- 1.8, 99.3 +/- 5.2, and 6.9 +/- 0.6 FU/100 microg respectively in the control group, all P < 0.01). CONCLUSION: Environmental toxins induce proteolytic stress marked by dysfunction of ubiquitin proteasome and accumulation of alpha-synuclein and ubiquited proteins.

Mechanism of over-activation in direct pathway mediated by dopamine D1 receptor in rats with levodopa-induced dyskinesia.

OBJECTIVE: To study the changes of prodynorphin (PDyn) gene expression and dopamine and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) phosphorylation in rats with levodopa-induced dyskinesia (LID), and to explore the mechanism of over-activation in direct pathway mediated by dopamine D1 receptor. METHODS: Parkinson's disease (PD) rats were received levodopa (10 mg/kg, i.p.) for 28 d to get the LID rats. According to the behavior scale, LID rats were divided into mild (n = 8) and severe (n = 16) groups. On day 29, 8 rats in severe LID group were given an acute intraperitoneal injection of MK-801 (0.1 mg/kg) 15 min before levodopa treatment (MK-801 group, n = 8). The normal rats received same course and dosage of levodopa as the control group (n = 8). Hybridization in situ was used to measure the expression of PDyn mRNA in striatum. Protein and mRNA levels of total DARPP-32 and phospho-Thr-34 DARPP-32 level were measured by immunoblotting and RT-PCR, respectively. RESULTS: The levels of PDyn mRNA and phospho-Thr-34 DARPP-32 increased significantly in LID rats compared with control rats (P < 0.01), and they also increased markedly in severe LID group compared with mild group (P < 0.01). CONCLUSION: Phospho-Thr-34 DARPP-32 level was increased in LID rats, which contributed to the over-activation of direct pathway mediated by dopamine D1 receptor.

[In vitro induction and expansion of dendritic cells from rat bone marrow and their characterization].

AIM: To induce and expand dendritic cells (DC) from rat bone marrow in vitro and identify their biological characterization. METHODS: The rat bone marrow cells were collected and cultured for 48 hours and the floating cells were removed. Then IL-4 and GM-CSF were added into the fresh medium. After 2 weeks, the morphological character of the cultured DCs was observed under light microscope and transmission electron microscope. Expressions of MHC class II molecule, B7-1 and B7-2 were detected by flow cytometry. The cultured DCs were co-cultured with allogenic T cells derived from rat spleen. T cell proliferation was measured by MTT colorimetry. RESULTS: The cultured DCs had the typical morphological characterization of DC, and the expression rates of MHC class II molecule, B7-1 and B7-2 were 74.2%, 81% and 76% respectively. The cultured DCs could notably stimulate the proliferation of allogeneic T cells. CONCLUSION: The adherent culture of rat bone marrow cells, and co-culture with IL-4 and GM-CSF can obtain a number of high purity of DCs, which lay the foundation for study on DC's function.

Effect of thrombin on blood brain barrier permeability and its mechanism.

BACKGROUND: Previous studies have indicated that thrombin (TM) may play a major role in brain edema after intracerebral hemorrhages (ICHs). However, the mechanism of TM-induced brain edema is poorly understood. In this study, we explored the effect of TM on the permeability of the blood brain barrier (BBB) and investigated its possible mechanism, aiming at providing a potential target for brain edema therapy after ICHs. METHODS: TM or TM + cathepsin G (CATG) was stereotaxically injected into the right caudate nucleus of Sprague-Dawley rats in vivo. BBB permeability was measured by Evans-Blue extravasation. Brain water content was determined by the dry-wet weight method. Brain microvascular endothelial cells were then cultured in vitro. After TM or TM + CATG was added to the endothelial cell medium, changes in the morphology of cells were dynamically observed by phase-contrast light microscopy, and the expression of matrix metalloproteinase-2 (MMP-2) protein was measured by immunohistochemical method. RESULTS: BBB permeability increased at 6 hours after a TM injection into the ipsilateral caudate nucleus (P < 0.05), peaked between 24 hours (P < 0.01) and 48 hours (P < 0.05) after the injection, and then declined. Brain water content changed in parallel with the changes in BBB permeability. However, at all time points, BBB permeability and brain water content after a TM + CATG injection were not significantly different from the respective parameters in the control group (P > 0.05). TM induced endothelial cell contraction in vitro in a time-dependent manner and enhanced the expression of MMP-2 protein. After incubation with TM + CATG, cell morphology and MMP-2 expression did not change significantly as compared to the control group (P > 0.05). CONCLUSIONS: Increased BBB permeability may be one of the mechanisms behind TM-induced cerebral edema. TM induces endothelial cell contraction and promotes MMP-2 expression by activating protease activated receptor-1 (PAR-1), possibly leading to the opening of the BBB.