Chronic endurance exercise increases pancreatic weight, protein content and enzyme activity through hypertrophy of acinar cells.
BackgroundHabitual exercise and dietary restriction are commonly recommended to prevent or ameliorate obesity and lifestyle-related diseases, including fatty liver. This study investigated the effects of habitual exercise and dietary restriction on hepatic triglyceride (TG) levels, serum leptin levels, and histological adipocyte size in periepididymal adipose tissue from Zucker fatty (ZF) rats.MethodsSix-week-old male ZF rats were randomly assigned to one of three groups: sedentary (Sed), sedentary and dietary restriction (Sed + DR), and training and dietary restriction (Tr + DR). Male Zucker lean (L) rats were used as control animals. All rats had access to water and the allowed quantity of food ad libitum. The rats in the Sed + DR and Tr + DR groups were fed a 30% restricted diet, while those in the Tr + DR group exercised voluntarily on a wheel ergometer. After 12 weeks, the rats were sacrificed for a histological examination of their liver and periepididymal adipose tissue. Hepatic and serum TG, serum total cholesterol, glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, free fatty acid, and leptin levels were also measured.ResultsThe hepatic TG levels were significantly higher in the Sed + DR group than in the L (P < 0.001) and Sed (P < 0.05) groups. By contrast, the hepatic TG levels in the Tr + DR group were significantly lower than those in the Sed (P < 0.05) and Sed + DR (P < 0.001) groups, but not significantly different from the L group values. The periepididymal adipocytes were significantly larger in the Sed, Sed + DR, and Tr + DR groups than in the L group (P < 0.001) and were significantly smaller in the Tr + DR group compared to the Sed and Sed + DR groups (P < 0.001).ConclusionsOur results suggest a relationship between lipid metabolism and the size of adipose cells in ZF rats. Exercising plays an important role in decreasing hepatic TG levels, serum leptin levels, and the size of adipose cells.
The effect of chronic exercise on pancreatic enzyme activity and basal pancreatic secretion was investigated in rats. Male Wistar rats were divided into three groups of ten rats each. In a trained (T) group, the animals were exercised on a treadmill at 35 m x min(-1) for 60 min, 5 days x week(-1). A free-fed control (C) group and a pair-fed control (PFC) group were kept sedentary. Food intake in the PFC group was restricted to the T group levels. After 6 weeks, pancreas wet mass per unit of body mass was significantly larger in the T group in comparison to the C and PFC groups. Protein content, and amylase and lipase activities of the pancreas were significantly higher in the T group in comparison to the C and PFC groups. Basal amylase but not bile-pancreatic juice volume was higher in the T group than in the other two groups. There were no significant differences between groups C and PFC in any of the above parameters. These results would suggest that pancreatic enzyme synthesis and basal secretion are accelerated with physical endurance training. This adjustment would be a beneficial adaptation to chronic endurance exercise, which requires a large energy supply from food.
We investigated the effects of habitual exercise and diet restriction on the hepatic fat accumulation in Zucker fatty rats. Male 6-week-old Zucker fatty rats were divided into obese (Ob), diet restriction (DR), and diet restriction + exercise (DR + Ex) groups. Male Zucker lean rats (L) were used as a control group. The rats in the L and Ob groups were maintained on ad libitum diets. The rats in the DR and DR + Ex groups were fed a 30% restricted diet. The rats in the DR + Ex group exercised voluntarily on a wheel ergometer. After 6 weeks of intervention, the serum free fatty acid and leptin levels in the Ob group were significantly higher than those in the L group. In the Ob group, the hepatic triglyceride content was higher than that in the L group and hepatocyte fat infiltration was observed on haematoxylin and eosin staining. These changes were suppressed by DR + Ex, but not by the DR intervention. These results suggest that habitual exercise inhibits fat accumulation in the liver of Zucker fatty rats.
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