Effect of exercise-training on the metabolic manifestations of streptozotocin-induced diabetes in the rat

Abstract

Summary. Streptozotocin-induced insulin deficiency of a moderate degree was produced in exercisetrained and sedentary young rats, and determinations made of subsequent changes in plasma glucose, triglyceride, and insulin concentrations. Exercise-training attenuated the rise in both plasma glucose and triglyceride concentrations associated with insulin deficiency. Plasma insulin levels were, if anything, lower in exercise-trained rats. Thus, the beneficial effects of exercise-training on plasma glucose and triglyceride concentrations could not be due to the preservation of endogenous insulin secretion, and appear to be secondary to enhanced insulin sensitivity.Key words: Streptozotocin, exercise-training, diabetic hypertriglyceridaemia, insulin deficiency, glucose, triglyceride, insulin.Plasma concentrations of glucose and triglyceride (TG) are elevated in rats with even a moderate degree of streptozotocin-induced insulin deficiency [1]. There is reason to believe that all of these metabolic abnormalities might be ameliorated if insulin sensitivity could be enhanced, and recent evidence has demonstrated that exercise-training can lead to increased insulin sensitivity in normal rats [2,3]. Given these observations, it seemed reasonable to see if exercisetraining could prevent the rise in plasma glucose and TG concentrations that develop in rats with streptozotocin-induced insulin deficiency.vidually in exercise wheel cages (Wahman Co., Timonium, Maryland, USA), and allowed to run at their own pace. The cages, as supplied by the manufacturer, consist of a rotating wheel cage with the number of revolutions/day recorded by a cyclometer attached to the wheel axis plus an adjoining feed cage. In order to maximize exposure to the wheel, we replaced the feed cage attachment with a small feeding trough large enough to hold 4-5 days food supply. Thus, the exercising animals remained entirely in the wheel portion of the cage to run at will and feed on laboratory chow ad lib from the attached feeding trough. Preliminary studies indicated that approximately two out of three of the rats placed in the modified exercise wheel cages showed a progressive increase in running activity and average between 2.0-2.5 miles/day after 10 days exposure. Animals unable to attain a level of 2.5 miles/day were excluded from the study.Two kinds of experiments were conducted. In the first series of experiments the rats were divided into two groups at the outset -exercised and sedentary -and maintained in this manner for 21 days. On the morning of day 21, all animals were injected in the tail vein with 40 mg/kg of streptozotocin (SZ). Following this, the rats were returned to their original status for another 10 days: i. e., sedentary rats were placed back in conventional cages and exercise-trained rats placed back in exercise cages. Food was removed at 0800 h on the morning of day 31, rats were decapitated at 1300 h, and blood taken for determination of plasma glucose [4], TG [5], and insulin [6] concentrations. All biochemical determinations we...

The effect of metformin and exercise on serum lipids, nitric oxide synthase and liver nitric oxide levels in streptozotocin-nicotinamide induced diabetic rats

“…In our study, serum glucose levels decreased after exercise intervention in DE group (p<0.05). This result supports Reaven's results demostrating "exercise decreases glucose concentrations in animal models of type 2 diabetes" (Reaven and Chang, 1981). The reduction of glucose levels in exercise group may be associated with a compensatory function in pancreatic β-cells.…”

A high-MUFA diet alone does not affect ketone body metabolism, but reduces glycated hemoglobin when combined with exercise training in diabetic rats

“…The results showed that diabetic rats in the EX group did not exhibit any improvement in glucose metabolism, while their sedentary counterparts had an average glucose level of more than 400 mg/dL at the end of the 12-week experiment. This finding is consistent with previous investigations, which indicated that exercise training improved glucose homeostasis in rats with mild STZinduced diabetes [34][35][36], but not in those with a severe diabetic state [6,9,37,38]. In this study, MUFA diet tended to reduce fasting plasma glucose levels, but no additional reduction was seen in combination with exercise.…”

Physical training reverses defect in 3-ketoacid CoA-transferase activity in skeletal muscle of diabetic rats

“…Physical conditioning is also known to be beneficial in animal models with diabetes mellitus. Previous studies have shown that endurance exercise training improves glucose homeostasis in rats with mild experimental diabetes mellitus (28,31,32). Studies from our laboratory (22) have shown that the increased death rate of chronically diabetic rats submitted to acute experimental myocardial infarction can be reversed by a previous program of physical training even in the absence of an improvement in plasma glucose or insulin levels (10,21).…”