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Aim: This study aimed to investigate the effects of melatonin (ME) on insulin resistance (IR) and signaling (IS), proinflammatory cytokine levels, and lipid profiles in pinealectomyzed (PNX) rats with periodontal disease (PD)., Main Methods: One hundred and forty-four rats (age = 40 days) were distributed into 8 groups: 1) control (CN); 2) PD only; 3) PNX only; 4) PNX and PD (PNXPD); 5) CN treated with ME (CNM); 6) PD treated with ME (PDM); 7) PNX treated with ME(PNXM); 8) PNX and PD treated with ME(PNXPDM). The PNX groups were subjected to pinealectomy at 40 and at 60 days of age. The animals were then subjected to PD induction in the mandibular first molars. After PD induction, the ME replacement therapy (MERT-5 mg/kg body weight) was performed using water for 28 days. After this period, the plasma concentration of glucose, insulin, TNF, IL-6, triglycerides, total cholesterol, HDL-cholesterol, LDL-cholesterol, and VLDL-cholesterol and the HOMA-IR index were determined. Akt serine phosphorylation status in the white adipose tissue, gastrocnemius muscle, and rat liver were also evaluated., Key Findings: PD, PNX, and PNXPD groups showed an increase in IR with elevated plasma levels of insulin and TNF compared to CN group. PNX and PNXPD groups presented alteration in lipid profile compared to CN group. MERT improved all of the analyzed parameters. No difference was observed in the IS among different groups., Significance: The results suggest that MERT efficiently prevents IR, improves lipid profile, and increases plasma levels of insulin and TNF in PD and PNX rats., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Introduction: Our previous studies have shown that periapical lesions (PLs) in rats cause systemic disorders such as increased tumor necrosis factor-α plasma levels, insulin resistance, and impairment in insulin signal transduction in muscle tissue. However, the mechanisms involved in these alterations are not fully understood. Under chronic inflammatory conditions such as obesity, it has been shown that the skeletal muscle is affected by inflammation, and the number of resident macrophages that are associated with impairments of insulin action and sensitivity is increased. This study aimed to investigate the presence of macrophages, activation of inflammatory pathways in muscle tissue, glycemia, and insulinemia of rats with PLs., Methods: Sixty Wistar rats were distributed into a control group; a group with 1 PL (1PL), which was induced in the right maxillary first molar; and a group with 4 PLs (4PL), which were induced in the right upper and lower first and second molars. We quantified macrophage content by immunohistochemistry for the F4/80 protein. We evaluated Jun N-terminal kinase and IKKα/β phosphorylation status in the muscle tissue by Western blotting. Serum levels of lipopolysaccharide (LPS) and HSP70 and plasma levels of glucose and insulin were assessed by using commercial kits., Results: The 1PL and 4PL groups showed increase in macrophage content, IKKα/β, and Jun N-terminal kinase phosphorylation status, serum LPS and HSP70 levels, and insulin resistance and no changes in glycemia and insulinemia compared with the control group. There was no difference in these parameters between the 1PL and 4PL groups., Conclusions: PLs promoted an increase in macrophage infiltration, activation of inflammatory pathways in muscle tissue, and serum concentrations of HSP70 and LPS in rats. The present study improves the knowledge on the impact of oral inflammations on the development of systemic alteration, which can induce insulin resistance., (Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)