Abstract
OBJECTIVES:Dietary omega-3 fatty acids have been efficacious in decreasing serum cholesterol levels and reducing the risk of cardiovascular disease. However, the metabolic and molecular changes induced by the omega-3 fatty acid α-linolenic acid (ALA), which is found in linseed oil, are not fully understood. In this study, we showed a correlation between ALA and insulin resistance, inflammation and endoplasmic reticulum stress (ERS).METHODS:We studied 40 male mice (C57/BL6) divided into 4 groups: a control (C) group, a control + omega-3/ALA (CA) group, a high-fat diet (HFD) (H) group and a high-fat diet + omega-3/ALA (HA) group. For 8 weeks, the animals in the H and HA groups were fed a high-fat (60%) diet, while the animals in the C and CA groups received regular chow. The diets of the CA and HA groups were supplemented with 10% lyophilized ALA.RESULTS:ALA supplementation improved glucose tolerance and reduced insulin resistance, as measured by intraperitoneal glucose tolerance tests and the homeostasis model assessment for insulin resistance, respectively. In addition, ALA reduced hepatic steatosis and modified the standard fat concentration in the liver of animals fed an HFD. Dietary ALA supplementation reduced the serum levels of interleukin 6 (IL-6), interleukin 1 beta (IL-1β) and monocyte chemoattractant protein-1 (MCP-1), increased the expression of important chaperones such as binding immunoglobulin protein (BIP) and heat shock protein 70 (HSP70) and reduced the expression of C/EBP-homologous protein (CHOP) and X-box binding protein 1 (XBP1) in hepatic tissues, suggesting an ERS adaptation in response to ALA supplementation.CONCLUSIONS:Dietary ALA supplementation is effective in preventing hepatic steatosis; is associated with a reduction in insulin resistance, inflammation and ERS; and represents an alternative for improving liver function and obtaining metabolic benefits.
Highlights
Obesity has become an important global public health problem resulting in an increased prevalence of chronic diseases such as type 2 diabetes, metabolic syndrome and coronary heart disease [1]
Many studies are trying to understand how omega-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) of animal origin, can fight diseases related to metabolic syndrome
No difference in body weight gain was observed between the groups fed control chow and an high-fat diet (HFD), as expected, this treatment induced the onset of typical phenotypes of metabolic syndrome
Summary
Obesity has become an important global public health problem resulting in an increased prevalence of chronic diseases such as type 2 diabetes, metabolic syndrome and coronary heart disease [1]. A high-fat diet (HFD) is used as a model to induce obesity and/or insulin resistance by inducing metabolic complications and increased inflammation [2,3,4]. Hepatic steatosis is a metabolic complication that is associated with an HFD [4] and has a high global incidence. Received for publication on February 23, 2018. Accepted for publication on May 28, 2018
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