EXERCISE TRAINING HAS A LONG-LASTING EFFECT ON PREVENTION OF NON-INSULIN-DEPENDENT DIABETES-MELLITUS IN OTSUKA-LONG-EVANS-TOKUSHIMA FATTY RATS

Exercise training has been shown to be effective in preventing the dev elopment 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 develop ment of NIDDM lasts in this model, six male OLETF rats each were assig ned to training (1) for a whole experimental period, from 7 to 28 week s of age (E-E); (2) for the first half of the period, from 7 to 15 wee ks 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 66 9 g and had abdominal fat deposits of 13.9, 21.3, 38.2, and 76.0 g, re spectively. 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 gr eater 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 ap peared slightly enlarged and fibrotic, although significantly less tha n those of islets of S-S rats. These results demonstrate that the prev entive effect of exercise training against the development of NIDDM la sts for at least 3 months after the cessation of exercise in this mode l. (C) 1996 by W.B. Saunders Company