Exercise training has a long-lasting effect on prevention of non—insulin-dependent diabetes mellitus in Otsuka-Long-Evans-Tokushima fatty rats☆

Abstract 

Exercise training has been shown to be effective in preventing the development of non—insulin-dependent diabetes mellitus (NIDDM) in a model rat (Otsuka-Long-Evans-Tokushima Fatty [OLETF]). For determination of how long a preventive effect of exercise training against the development of NIDDM lasts in this model, six male OLETF rats each were assigned to training (1) for a whole experimental period, from 7 to 28 weeks of age (E—E); (2) for the first half of the period, from 7 to 15 weeks of age (E—S); and (3) for the second half of the period, from 16 to 28 weeks of age (S—E). In addition, eight male OLETF rats were given no exercise during the experimental period (S—S). At 28 weeks of age, E—E, E—S, S—E, and S—S rats, weighed averages of 514, 542, 557, and 669 g and had abdominal fat deposits of 13.9, 21.3, 38.2, and 76.0 g, respectively. At 28 weeks of age, the cumulative incidence of NIDDM in S—S was 100%, while none of the trained rats were diabetic. The glucose infusion rate (GIR) during a hyperinsulinemic euglycemic clamp test, an index of insulin sensitivity, in the E—E group was significantly greater than that in the S—S group. The values in the E—S and S—E groups were slightly, but not significantly, less than that in the E—E group. Morphologic studies on the pancreas of E—E rats and S—E rats showed minimal changes of islets, whereas sections of islets from E—S rats appeared slightly enlarged and fibrotic, although significantly less than those of islets of S—S rats. These results demonstrate that the preventive effect of exercise training against the development of NIDDM lasts for at least 3 months after the cessation of exercise in this model.

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