The purpose of the present study was to determine the effects of an exercise training programme in high-fat-fed rats on in vitro lipolysis in a visceral (mesenteric) and a non-visceral fat depot (retroperitoneal) and its relationship to perilipin content. Two groups of female rats were fed a high-fat diet (42 % as energy) for 8 weeks, one remaining sedentary (Sed) and the other being exercise trained (Tr) for this entire period. Rats were killed after 2 and 8 weeks of their respective treatment. The significantly (P,0·01) higher levels in mesenteric and retroperitoneal fat pad weights, plasma leptin, NEFA and glucose observed with time in Sed high-fat-fed rats were significantly (P,0·05) attenuated in Tr animals. Isoproterenol-stimulated (10 25 -10 24 M) lipolysis in the mesenteric, but not in the retroperitoneal tissue, was significantly (P, 0·05) lower (about 57 %) in Tr than in Sed rats after 8 weeks of high-fat feeding. The isoproterenol-stimulated lipolysis in the mesenteric tissue of 8-week Tr high-fat-fed rats was lowered to the level measured in 2-week fat-fed rats although mesenteric fat accumulation was still significantly (P, 0·01) higher in 8-than in 2-week Tr rats. Perilipin content (Western blot) was not affected by the exercise training programme. These results indicate that exercise training resulted in a reduction in the high-fat diet-induced elevated levels of lipolysis in the mesenteric tissue. This response appears to be independent of the perilipin content.

The purpose of the present study was to determine the time course of changes in in vitro lipolysis and in perilipin content (Western blot) in the mesenteric and/or the retroperitoneal fat depots in relation to the development of hepatic steatosis in high-fat diet-fed rats. Female Sprague-Dawley rats were submitted to a high-fat diet (HF diet; 42 % as kJ) or a standard diet (SD diet) for 1, 2, 3 or 8 weeks. Fat accretion in the mesenteric and retroperitoneal tissues was higher (P,0·01) in HF diet-fed than in SD diet-fed rats as soon as 1 week after the beginning of the diet. Liver triacylglycerol concentrations were significantly (P,0·01) higher in HF diet-fed than in SD diet-fed rats throughout the experiment, the highest values being reached at week 2 of the diet. Basal and stimulated lipolysis (10 24 to 10 27 M-isoproterienol) in the mesenteric and retroperitoneal fat depots was not changed during the first 3 weeks, regardless of the diet. Lipolysis in the mesenteric adipose tissue in the basal and stimulated states was, however, higher (P,0·01) in HF diet-fed than in SD diet-fed rats after 8 weeks of the diets. There were no significant (P.0·05) effects of diet and time on perilipin content of mesenteric tissue. In spite of a rapid fat accretion, the present results do not provide any evidence of a rapid (3 weeks) increase in in vitro lipolysis in intra-abdominal fat depots upon the undertaking of an HF diet at a time where liver lipid infiltration is the most significant.