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1.
Free Radic Biol Med ; 141: 393-407, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31279968

RESUMO

Exposure to fine particular matter (≤2.5 µM, PM2.5) contributes to increased risk of obesity and type 2 diabetes. Hydroxytyrosol (HT), a simple polyphenol found in virgin olive oil, is considered to be beneficial for cardiovascular and metabolic disorders. The current study determined whether HT could improve PM2.5-induced adiposity and insulin resistance (IR), and explored the underlying mechanisms. Fifteen adult female C57BL/6j mice on a chow diet were randomly divided into three groups receiving (1) sterile PBS, (2) PM2.5 suspended in sterile PBS (1 mg/mL) and (3) PM2.5+HT (50 mg/kg/day). PM2.5/PBS exposure was administered by oropharynx instillation every other day and HT supplementation was achieved by gavage every day. Four-week PM2.5 exposure did not affect body weight, but significantly increased visceral fat mass. The abdominal adiposity coincided with adipocyte hypertrophy and proliferation in visceral white adipose tissue (WAT), as well as decreased metabolic activity in brown adipose tissue and subcutaneous WAT. PM2.5 enhanced the oxidative stress by diminishing antioxidant enzyme activities in liver and serum, whereas contents of 4-hydroxynonenal (4-HNE), malondialdehyde (MDA) levels in liver and serum were elevated. These changes were accompanied by macrophage infiltration and activation of NF-κB pathway in the liver. Moreover, PM2.5 exposure led to glucose intolerance and insulin insensitivity, impaired hepatic glycogenesis, and decreased insulin-stimulated Akt phosphorylation in peripheral tissues. Importantly, HT treatment prevented PM2.5-induced visceral adipogenesis, oxidative stress, hepatic inflammation and NF-κB activation, systemic and peripheral IR. In vitro, after HepG2 cells were incubated with PM2.5 (0, 5, 25, 50, 100 and 200 µg/mL), reduced glutathione depletion and 4-HNE, 8-hydroxy-2'-deoxyguanosine, MDA increment in a dose-dependent manner were observed; likewise, insulin-stimulated glucose uptake decreased in a dose-dependent manner. Further, with antioxidant NAC and NF-κB inhibitor PDTC, we confirmed that HT attenuated PM2.5-induced IR through restraining NF-κB activation evoked by oxidative stress. In addition, HT could expand gut microbiota richness, reduce pathogenic bacteria and accommodate the microbial architecture in PM2.5-exposed mice, which were correlated with parameters of adiposity, oxidative stress and glycometabolism. HT could effectively correct imbalanced oxidative stress triggered by PM2.5, in turn ameliorated NF-κB pathway and insulin signaling. Gut microbiota may mediate the actions of HT.

2.
Front Microbiol ; 10: 390, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30886607

RESUMO

Obesity is a common chronic metabolic disease that is harmful to human health and predisposes the affected individuals to a cluster of pathologies. Insulin resistance (IR) is one of the most frequent complications of obesity. Hydroxytyrosol (HT) may reduce obesity and IR in high-fat diet (HFD)-fed mice; however, the mechanism underlying is still unknown. Systemic low-grade inflammation and intestinal dysfunction are thought to be associated with obesity and IR. In this study, we found that HFD feeding for 8 weeks altered the intestinal microbiota, injured intestinal barrier function, increased endotoxin release into the blood, enhanced the expression of inflammatory factors (TNF-α, IL-1ß, IL-6) and lipid accumulation in liver, caused obesity, and aggravated IR via the JNK/IRS (Ser 307) pathway in HFD mice. We also found that HT gavage could reverse those effects and the beneficial effects of HT were transferable through fecal microbiota transplantation. Our data indicate that HT can improve obesity and IR by altering the composition of the intestinal microbiota and improving integrity of the intestinal wall. We propose that HT replenishment may be used as a dietary intervention strategy to prevent obesity and IR.

3.
Guang Pu Xue Yu Guang Pu Fen Xi ; 31(9): 2525-8, 2011 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-22097863

RESUMO

Yb3+ doped double-cladding large-mode-area micro-structured optical fibers (Micro-structured fibers, MSF) are the ideal medium for the super high-power optical fiber laser applications. In the present paper, the authors fabricated the Yb3+ doped silica-based glass using the method of non-chemical vapor deposition, and fabricated the Yb3+ doped double-cladding large-mode-area MSF by stack-drawing method using this glass as the core of MSF, according to the design requirements. Fluorescence spectrum of the MSF was obtained using Ti: sapphire femtosecond laser with the wavelength of 975 nm and LD laser with the wavelength of 980 nm as pumping source. The experimental results show that the optical fiber has strong fluorescence at the wavelength of 1 050 nm, and it can inhibit generation of cooperative luminescence effectively.

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