Impact of metformin treatment and swimming exercise on visfatin levels in high-fat-induced obesity rats

Abstract

Objective: Visfatin is a recently discovered adipocytokine that contributes to glucose and obesityrelated conditions. Until now, its responses to the insulin-sensitizing agent metformin and to exercise are largely unknown. We aim to investigate the impact of metformin treatment and/or swimming exercise on serum visfatin and visfatin levels in subcutaneous adipose tissue (SAT), peri-renal adipose tissue (PAT) and skeletal muscle (SM) of high-fat-induced obesity rats. Materials and methods:Sprague-Dawley rats were fed a normal diet or a high-fat diet for 16 weeks to develop obesity model. The high-fat-induced obesity model rats were then randomized to metformin (MET), swimming exercise (SWI), or adjunctive therapy of metformin and swimming exercise (MAS), besides high-fat obesity control group and a normal control group, all with 10 rats per group. Zoometric and glycemic parameters, lipid profile, and serum visfatin levels were assessed at baseline and after 6 weeks of therapy. Visfatin levels in SAT, PAT and SM were determined by Western Blot. Results: Metformin and swimming exercise improved lipid profile, and increased insulin sensitivity and body weight reduction were observed. Both metformin and swimming exercise down-regulated visfatin levels in SAT and PAT, while the adjunctive therapy conferred greater benefits, but no changes of visfatin levels were observed in SM. Conclusion: Our results indicate that visfatin down-regulation in SAT and PAT may be one of the mechanisms by which metformin and swimming exercise inhibit obesity.Arq Bras Endocrinol Metab. 2014;58(1):42-7 Keywords Endocrinology; metabolic syndrome; adipocytokine RESUMO Objetivo: A visfatina é uma adipocina recentemente descoberta que contribui com as condições relacionadas à glicose e à obesidade. Até hoje, pouco se sabe da sua resposta à metformina, um agente sensibilizador de insulina, e ao exercício. Nosso objetivo foi investigar o impacto do tratamento com metformina e/ou da natação sobre a visfatina no soro e no tecido adiposo subcutâneo (TAS), tecido adiposo perirrenal (TAP) e músculo esquelético (ME) em ratos com obesidade induzida por dieta com alto teor de gordura. Materiais e métodos: Ratos Sprague-Dawley foram alimentados com uma dieta normal ou com alto teor de gordura por 16 semanas para o desenvolvimento de um modelo de obesidade. Os ratos do modelo de obesidade foram, então, randomizados para a metformina, natação ou terapia de combinação com metformina e natação, além do grupo controle de obesidade induzida por alto teor de gordura e do grupo controle normal. Cada grupo apresentava 10 ratos. Parâmetros zoométricos e glicêmicos, perfil lipídico e níveis de visfatina sérica foram avaliados no momento inicial e após seis semanas de tratamento. Os níveis de visfatina em TAS, TAP e ME foram determinados por Western Blot. Resultados: A metformina e a natação melhoraram o perfil lipídico e aumentaram a sensibilidade à insulina, com redução do peso corporal. Tanto a metformina quanto a natação levaram à regulação para baixo do...

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