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ABSTRACT
25 Regular physical activity improves glucose tolerance and decreases adiposity. Our aim
26 was to investigate the effects of exercise training on subcutaneous (inguinal) and visceral
27 (parametrial) adipose tissue in rats that were fed a chow diet (13% fat) or made insulin
28 resistant by a high fat diet (60% fat). Sprague Dawley rats performed four weeks of
29 voluntary wheel running or were kept as sedentary controls. The training groups fed the
30 chow and high fat diet achieved similar running distances (8.8 ± 1.8 and 9.3 ± 1.9 km/day
31 respectively). Training improved oral glucose tolerance in chow fed rats and prevented
32 the glucose intolerance that occurred in sedentary rats fed the high fat diet. In both
33 subcutaneous and visceral adipose tissue, the high fat diet-induced increases in fat pad
34 weight (67% and 133%, respectively), adipocyte size (20% and 43%), and cell number
35 (36% and 65%) were completely prevented by exercise training. Cytokine mRNA
36 expression in visceral fat did not change with exercise training. However, in
37 subcutaneous fat, training actually increased mRNA expression of several cytokines
38 (IL-6: 80%, p<0.05; TNF- α: 100%, p<0.05; IL-1Ra: 57%, p=0.08), with no detectable
39 increases in serum cytokine concentrations. In summary, exercise training can overcome
40 high fat diet-induced impairments in glucose tolerance and increases in adipocyte size,
41 cell number, and fat pad mass. Improved glucose tolerance was accompanied by an
42 increase in cytokine gene expression in subcutaneous fat. This finding raises the
43 possibility of a specific role of subcutaneous adipose tissue in adaptive responses to
44 exercise training.
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