Obesity-associated Gingival Vascular Inflammation and Insulin Resistance.
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ABSTRACT: Obesity is a risk factor for periodontitis, but the pathogenic mechanism involved is unclear. We studied the effects of insulin in periodontal tissues during the state of obesity-induced insulin resistance. Gingival samples were collected from fatty (ZF) and lean (ZL, control) Zucker rats. Endothelial nitric oxide synthase (eNOS) expression was decreased, and activities of protein kinase C (PKC) ?, ß2, ?, and ? isoforms were significantly increased in the gingiva from ZF rats compared with those from ZL rats. Expression of oxidative stress markers (mRNA) and the p65 subunit of NF-?B was significantly increased in ZF rats. Immunohistochemistry revealed that NF-?B activation was also increased in the gingival endothelial cells from transgenic mice overexpressing NF-?B-dependent enhanced green fluorescent protein (GFP) and on a high-fat vs. normal chow diet. Analysis of the gingiva showed that insulin-induced phosphorylation of IRS-1, Akt, and eNOS was significantly decreased in ZF rats, but Erk1/2 activation was not affected. General PKC inhibitor and an anti-oxidant normalized the action of insulin on Akt and eNOS activation in the gingiva from ZF rats. This provided the first documentation of obesity-induced insulin resistance in the gingiva. Analysis of our data suggested that PKC activation and oxidative stress may selectively inhibit insulin-induced Akt and eNOS activation, causing endothelial dysfunction and inflammation.
SUBMITTER: Mizutani K
PROVIDER: S-EPMC4023466 | biostudies-literature | 2014 Jun
REPOSITORIES: biostudies-literature
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