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| Author(s): |
Guilherme da Silva Ferreira
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD) |
| Defense date: | 2017-10-04 |
| Examining board members: |
Marisa Passarelli;
Carlos Eduardo Negrão;
Maria Elizabeth Rossi da Silva
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| Advisor: | Marisa Passarelli |
| Abstract | |
Oxysterols modulate the development of atherosclerosis by mediating cholesterol synthesis, uptake and exportation as well as inflammation and cytotoxicity in the arterial wall. Regular physical exercise prevents and regresses atherosclerosis by improving lipid metabolism, reverse cholesterol transport and antioxidant defenses. AMP-activated protein kinase (AMPK) plays an important role in the beneficial metabolic adaptations of physical exercise. In macrophages, its activation is related to the enhancement in cholesterol efflux and reduction in LDL uptake. However, it is not clear whether exercise training benefits in atherosclerosis is mediated by its action in oxysterols concentrations, and whether this can be modulated by AMPK. The aim of this study was to evaluate the role of a 6-week aerobic exercise training program in dyslipidemic mice in the arterial and plasma accumulation of cholesterol and oxysterols subspecies; expression of genes related to oxysterols metabolisms in the aortic arch, and the effect of AMPK activation in macrophage on the concentration of oxysterols and expression of genes linked to oxysterols metabolism. Sixteen-week-old male apoE knockout mice fed a chow diet were included in the protocol. Animals were trained in a treadmill running, 15 m/min, 60 min, 5 days/week, during 6 weeks. Plasma lipids and glucose were determined by enzymatic techniques and glycosometer, respectively. Cholesterol in aortic arch and oxysterols were measured by gas chromatography/mass spectrometer. The expression of genes involved in lipid metabolism was determined by RT-qPCR. Results (mean ± SD) were compared by one-way ANOVA with Newman-Keuls posttest or Student\'s t-test. Body weight and plasma total cholesterol, TG, HDL-c, glucose, and oxysterols were similar among groups. The exercise training enhanced 7beta-hydroxycholesterol (70%) and reduced cholesterol (32%) in the aortic arch. In addition, exercise increased Cyp27a1 (54%), Cd36 (75%), cat (70%), Prkaa1 (AMPKalpha1) (40%) and Prkaa2 (AMPKalpha2) (51%) mRNA. No changes were observed in the expression of Abca1, Nr1h3 (LXRalpha) and Nr1h2 (LXRbeta). In macrophages, the activation of AMPK by AICAR, reduced 7beta-hydroxycholesterol level after stimulation by HDL2. Treatment with AICAR increased Abca1 (52%) and Cd36 (220%), decreased Prkaa1 (19%) e Cyp27a1 (47%), and did not change Abcg1, Nr1h3 e Nr1h2. In conclusion, in dyslipidemic mice aerobic exercise training increases the nonenzymatic-driven oxysterol, 7beta-hydroxycholesterol, which is related to the enhanced expression of Cd36. The rapid diffusion of oxysterols, as a complementary pathway for the reverse cholesterol transport, may also be favored by the increase and reduction of Cyp27a1 and Cyp7b1 expressions, respectively, which in turns favors 27-OH C desorption from cells. Together with its direct role in improving reverse cholesterol transport as previously reported, aerobic exercise training diminishes cholesterol accumulation in the arterial wall preventing atherosclerosis. Based on in vitro assays, the AMPK activation does not seem to contribute to the effect of exercise in increasing oxysterols (AU) | |
| FAPESP's process: | 14/07617-6 - Effect of aerobic exercise training in plasma and arterial distribution and concentration of oxysterols in dyslipidemic mice |
| Grantee: | Guilherme da Silva Ferreira |
| Support Opportunities: | Scholarships in Brazil - Master |