Eicosapentaenoic acid actions on adiposity and insulin resistance in control and high-fat-fed rats: role of apoptosis, adiponectin and tumour necrosis factor-α
2007
Perez-Matute, P. | Pérez-Echarri, N. | Martinez, J.A. | Marti, A. | Moreno-Aliaga, M.J.
n-3 PUFA have shown potential anti-obesity and insulin-sensitising properties. However, the mechanisms involved are not clearly established. The aim of the present study was to assess the effects of EPA administration, one of the n-3 PUFA, on body-weight gain and adiposity in rats fed on a standard or a high-fat (cafeteria) diet. The actions on white adipose tissue lipolysis, apoptosis and on several genes related to obesity and insulin resistance were also studied. Control and cafeteria-induced overweight male Wistar rats were assigned into two subgroups, one of them daily received EPA ethyl ester (1 g/kg) for 5 weeks by oral administration. The high-fat diet induced a very significant increase in both body weight and fat mass. Rats fed with the cafeteria diet and orally treated with EPA showed a marginally lower body-weight gain (P=0.09), a decrease in food intake (P<0.01) and an increase in leptin production (P<0.05). EPA administration reduced retroperitoneal adipose tissue weight (P<0.05) which could be secondary to the inhibition of the adipogenic transcription factor PPARgamma gene expression (P<0.001), and also to the increase in apoptosis (P<0.05) found in rats fed with a control diet. TNFalpha gene expression was significantly increased (P<0.05) by the cafeteria diet, while EPA treatment was able to prevent (P<0.01) the rise in this inflammatory cytokine. Adiposity-corrected adiponectin plasma levels were increased by EPA. These actions on both TNFalpha and adiponectin could explain the beneficial effects of EPA on insulin resistance induced by the cafeteria diet.
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