As in man, canine obesity is associated with insulin resistance, dyslipidaemia and other chronic diseases. This study was designed to examine the effects of a nutritional supplement (green tea) on insulin sensitivity and plasma lipid concentrations in an obese insulin-resistant dog model. We also determined mRNA expression of two transcription factors, PPARg and PPARa, and some of their target genes, including GLUT4, lipoprotein lipase (LPL) and adiponectin. Obese dogs were divided into two groups: a green tea group (n 6); a control group (n 4). Dogs in the green tea group were given green tea extract (80 mg/kg per d) orally, just before their single daily meal, for 12 weeks. Insulin sensitivity (using a euglycaemic -hyperinsulinaemic clamp) and concentrations of plasma TAG, total cholesterol and NEFA were assessed in each group. Gene expression was measured in visceral and subcutaneous adipose tissues and in liver and skeletal muscle, by real-time PCR. At 12 weeks in the green tea group, mean insulin sensitivity index was 60 (SEM 11) % higher (P,0·05) and TAG concentration 50 (SEM 10) % lower (P,0·001), than baseline. PPARg, GLUT4, LPL and adiponectin expression were significantly higher in both adipose tissues, whilst PPARa and LPL expression were significantly higher in skeletal muscle, compared with baseline. These findings show that nutritional doses of green tea extract may improve insulin sensitivity and lipid profile and alter the expression of genes involved in glucose and lipid homeostasis.

In dog as in human, obesity is associated with insulin resistance, dyslipidemia and other chronic diseases. Epidemiological and laboratory studies have shown that green tea has a variety of health effects. The aim of this study was to examine the effects of a green tea supplementation at nutritional doses on insulin sensitivity and plasma lipid concentrations and expression of peroxysome proliferator activated receptor gamma (PPARγ) in a model of obese dog. Ten obese insulin resistant dogs were divided in 2 groups: a “Green tea” group (n = 6) and a control group (n = 4). Dogs of the Green tea group were given, for 12 weeks, a capsule of green tea extract (81 mg/kg/d) just before their single meal. Insulin sensitivity using euglycemic hyperinsulinemic clamp and plasma triglycerides, total cholesterol and free fatty acids concentrations were assessed in each group. Expression of PPARγ gene was studied in visceral and subcutaneous adipose tissue. In “Green tea” group, the insulin sensitivity index increased by 60 ± 11 % (p < .05), plasma triglycerides concentrations decreased by 50 ± 10 % (p < .001) and PPARγ expression significantly increased in both adipose tissues. These findings show that treatment with green tea extract at nutritional doses may reverse some obesity‐related metabolic disorders by improving insulin sensitivity, lipid profile, and PPARγ expression in visceral and subcutaneous adipose tissues.