Biomedical subjects

N Rieth

Publications and source records attributed to N Rieth.

3 recordsLinked to original sources

PubMed1997

Exercise training decreases body fat more in self-selecting than in chow-fed rats.

This study was designed to examine the influence of exercise training on body weight gain and feeding pattern in rats placed on a self-selection or a chow diet regimen. Adult, male, Wistar rats were submitted to daily 2-h treadmill exercise for 28 days (about 50% of VO2 max) at the beginning of the nocturnal period. Two other groups of rats were examined during the same time: a sedentary group that was deprived of food and water during the training session and a control group without any treatment. Food intakes were continuously recorded. For both feeding regimens, trained rats, relative to their respective controls, showed at the end of the experiment a reduction in body weight gain due to a reduced body fat deposit. Moreover, white adipose tissue (WAT) mass of self-selecting rats was smaller than in chow-fed rats. Exercise training decreased plasma glucose level in chow-fed rats and plasma insulin level in self-selecting rats. In self-selecting rats, food intake was slightly increased due to enhanced protein intake during the nocturnal period and fat intake increased both during the nighttime and daytime periods, whereas in chow-fed rats, food intake was decreased during the daytime period. These results show that, in rats placed on a self-selection regimen, exercise training increased fat consumption but reduced WAT. This could be a consequence of an increased lipolytic capacity of adipocytes in self-selecting trained rats. Thus, it appears from these results that the diet's carbohydrate-to-fat ratio can be an important parameter in shaping the interaction between exercise and body weight.

Adipose Tissue↗

PubMed1995

Exercise-training reduces BAT thermogenesis in rats.

In the energy balance equation, physical activity represents one component of energy expenditure. From various studies it appears that exercise-training does not affect clearly thermogenesis which depends on brown adipose tissue (BAT) activity. In the present work we examine how exercise-training can influence food intake and body weight regulation in relation to BAT thermogenesis. The proton conductance of the uncoupling protein of BAT was examined in male adult Wistar trained 2 h/day for 20 days and compared to that of sedentary (2 h of fasting instead of exercise) or control animals. All animals were provided with separate sources of the 3 macronutrients (protein, fat and carbohydrate) containing an identical percentage of vitamins, salt mixture and cellulose powder. At the end of training, rats were placed at 5 degrees C during 10 days, then during 4 days at 28 degrees C. This condition has been demonstrated to favour and amplify BAT responsiveness to moderate modifications of stimulation. The body weight of trained rats became significantly lower than that of the control and sedentary rats and this difference persisted all throughout the experiment. When placed at 5 degrees C, all rats increased their total ingestion: control rats enhanced fat intake, while sedentary and trained rats enhanced carbohydrate ingestion. When placed at 28 degrees C, all rats had identical total energy and that of the 3 items intakes. BAT proton conductance was about 40% lower in the trained compared with the sedentary plus the control rats. This indicated a lower BAT thermogenic activity in the trained animals. It could be concluded that exercise-training in rats induces negative energy balance; the reduced BAT activity could restrain weight loss and overeating.

Adipose Tissue, Brown↗

PubMed1994

Exercise training modifies nutrient self-selection in rats.

Few studies have examined the effects of exercise training on macronutrient self-selection in rats. It has been observed that trained rats decreased carbohydrate and increased fat and protein intakes. In the present experiment, total energy intake and macronutrient self-selection were examined in adult male rats placed on a self-selection regimen and submitted to 2 h of treadmill exercise daily for 20 days at the beginning of the nocturnal period. Two control groups of rats were examined during the same time: a sedentary group that was food and water deprived during the same 2 h while trained rats were exercising, and a control group that was examined only for body weight gain and 24-h food intake. Food intakes of sedentary and trained rats were continuously recorded. At the end of the experiment, body weight of trained rats was lower than that of sedentary and control rats. The 24-h cumulative intake of trained rats was significantly reduced; this reduction was due to a decrease in fat intake, whereas carbohydrate intake was increased. In sedentary rats, 24-h intake was not modified but fat intake was significantly increased from the beginning to the end of the experiment. During the first 6 h of the night, protein and fat intakes of trained rats were reduced, and carbohydrate ingestion remained the same. Daytime food intake represented only 8.7% of the 24-h intake. Exercise training significantly increased this intake. It is noteworthy that during the middle part of the day (3-9 h) trained rats significantly enhanced protein and carbohydrate ingestion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗