Tatsuhiro Matsuo

Beef tallow diet decreases β-Adrenergic receptor binding and lipolytic activities in different adipose tissues of rat

The effects of dietary fats consisting of different fatty acids on lipolytic activity and body fat accumulation were studied in rats. Sprague-Dawley male rats were meal-fed an isoenergetic diet based on either beef tallow or safflower oil for 8 weeks. Lipolytic activities in epididymal and subcutaneous adipose tissues were lower in the beef tallow diet group than in the safflower oil diet group. Body fat accumulation was greater in rats fed the beef tallow diet versus the safflower oil diet. Norepinephrine (NE) turnover rates used as an index of sympathetic activities in adipose tissues were lower in the beef tallow diet group. beta-Adrenergic receptor binding was determined with [3H]dihydroalprenolol. Binding affinities of beta-receptors in adipose tissues were significantly lower in the beef tallow diet group. Membrane fluidities of adipose tissues were also lower in the beef tallow diet group. Membrane fluidities were correlated with the affinities of the beta-receptor. We believe from these correlations that the decreases in beta-receptor binding affinities are due to the changes in membrane fluidities. The results of the present study suggest that intake of the beef tallow diet promotes body fat accumulation by reducing lipolytic activities resulting from lower beta-receptor binding and sympathetic activity in adipose tissues.

Effects of the menstrual cycle on excess postexercise oxygen consumption in healthy young women.

The effects of the menstrual cycle on excess postexercise oxygen consumption (EPOC) were studied in seven healthy young women aged 18 to 20 years. EPOC, resting metabolic rate (RMR), and energy expenditure during exercise (EEDE) in the fasting state were measured in the follicular and luteal phases. On the experimental days, subjects exercised for 60 minutes on a bicycle ergometer at an intensity of 60% maximal oxygen consumption (VO2max) followed by rest for 6 hours. The EPOC and RMR were significantly higher (P < .05) and the postexercise respiratory exchange ratio (RER) was significantly lower (P < .05) in the luteal phase versus the follicular phase, whereas differences in the EEDE and basal and exercise RER were negligible in both phases. Fat oxidation during the experimental period was significantly greater in the luteal phase (P < .05). These results suggest that exercise in the luteal phase results in greater postexercise energy expenditure and fat utilization than in the follicular phase.

Beef tallow diet decreases norepinephrine turnover rates in rat hypothalamus and cerebral cortex

The effects of dietary fats consisting of different fatty acids on norepinephrine (NE) turnover rates in various brain regions were studied in rats. Sprague-Dawley male rats were meal-fed isoenergetic diets based on safflower oil or beef tallow for 8 weeks. Body weight gain during the experimental period did not differ between the two groups of rats. The weights of brain regions were also similar in the two diet groups. Basal NE contents and turnover rates in the hypothalamus and cortex were significantly lower in rats fed the beef tallow diet versus the safflower oil diet. These results suggest that the beef tallow diet reduces noradrenergic functions in brain regions as compared with the safflower oil diet in rats.

Effects of dietary composition and exercise timing on substrate utilization and sympathoadrenal function in healthy young women

The effects of dietary composition (high-fat [FAT] or high-carbohydrate [CHO]) and exercise timing (preprandial exercise [Ex-] or postprandial exercise [-Ex]) on postprandial substrate utilization and sympathoadrenal function were studied in seven women aged 20 to 21 years. The experimental protocol included four different sessions (Ex-FAT, FAT-Ex, Ex-CHO, and CHO-Ex). The FAT and CHO diets provided 48% and 5% fat, respectively. On the experimental days, subjects ate a meal containing the same caloric energy at lunchtime, and they exercised for 30 minutes on a bicycle ergometer at an intensity of 60% maximal oxygen consumption (VO2max) before and after the meal, followed by rest for 3 hours. The resting respiratory quotient (RQ) was significantly lower (P < .05) with the FAT diet or postprandial exercise. The mean RQ during the experimental period was 0.78, 0.75, 0.81, and 0.77 in Ex-FAT, FAT-Ex, Ex-CHO, and CHO-Ex groups, respectively. The total area under the curve of serum norepinephrine (NE) as an index of NE secretion was significantly higher (P < .05) with the FAT diet or postprandial exercise (130.2, 175.8, 33.0, and 136.9 ng x mL(-1) x min, respectively). A negative correlation was observed between the RQ and the total area of NE (r = .49, P < .05). The serum thyroid hormone level was not influenced by dietary composition and exercise timing. These results suggest that postprandial exercise, especially after intake of a FAT diet, increases fat utilization via a slightly larger decrease in the RQ. This might be related to the sympathoadrenal system at rest and during exercise.

Brain [β-adrenergic receptor binding in rats with obesity induced by a beef tallow diet

We have previously reported that compared with safflower oil diet, feeding a beef tallow diet leads to a greater accumulation of body fat by reducing sympathetic activities. The present study examined the effects of dietary fats consisting of different fatty acids on alpha1- and beta-adrenergic receptor binding in the hypothalamus and cerebral cortex. Male Sprague-Dawley rats were meal-fed isoenergetic diets based on safflower oil (rich in n-6 polyunsaturated fatty acids) or beef tallow (rich in saturated fatty acids) for 8 weeks. Binding affinities of the beta-adrenergic receptor in the hypothalamus and cortex were significantly lower in the beef tallow diet group, but those of the alpha1-receptor did not differ between the two groups. The polyunsaturated to saturated fatty acid (P/S) ratio and fluidities of plasma membranes in the hypothalamus and cortex were lower in the beef tallow diet group than in the safflower oil diet group. These results suggest that the beef tallow diet decreases membrane fluidity by altering the fatty acid composition of plasma membranes in the hypothalamus and cerebral cortex of rat. Consequently, beta-adrenergic receptor binding affinities in the brain were lower in rats fed the beef tallow diet than in rats fed the safflower oil diet. We recognized that there is possible link between the membrane fluidity and the changes in affinity of beta-adrenoceptors in rat brain.

The effects of a high carbohydrate diet on postprandial energy expenditure during exercise in rats.

SummaryWhether or not a high intake of carbohydrate increases postprandial energy expenditure during exercise was studied in rats. The rats were meal-fed regularly twice a day (0800–0900 hours and 1800–1900 hours) on either a high carbohydrate (CHO) (carbohydrate/fat/protein = 70/5/25, % of energy) or high fat (FAT) (35/40/25) diet for 12 days. On the final day of the experiment, all of the rats in each dietary group were fed an evening meal containing equal amounts of energy (420 kJ · kg−1 body mass). After the meal, they were divided into three subgroups: pre-exercise control (PC), exercise (EX), and resting control (RC). The PC-CHO and PC-FAT groups were sacrificed at 2030 hours. The EX-CHO and EX-FAT groups were given a period of 3-h swimming, and then sacrificed at 2330 hours. The RC-CHO and RC-FAT groups rested after the meal and were sacrificed at 2330 hours. Total energy expenditure during the period 1.5 h from the commencement of exercise was higher in EX-CHO than in EX-FAT. The respiratory exchange ratio was also higher in EX-CHO than in EX-FAT, suggesting enhanced carbohydrate oxidation in the former. Compared with both PC-FAT and RC-FAT, the liver glycogen content of EX-FAT rats was significantly decreased by exercise. On the other hand, the liver glycogen content of both EX-CHO and RC-CHO was higher than that of PC-CHO rats. The glycogen content of soleus muscle of EX-FAT was slightly decreased during exercise, however, that of EX-CHO increased significantly. Thus postprandial energy expenditure during exercise was higher in the rats fed the CHO diet than in those fed the FAT diet, which could have been related to the increase of both liver and muscle glycogen storage during exercise in the former.

Effects of capsaicin on abdominal fat and serum free-fatty acids in exercise-trained rats

This study was undertaken to determine whether capsaicin may influence abdominal fat deposition and circulating free-fatty acids in exercise-trained rats. In addition, the contribution of beta-adrenergic stimulation to capsaicin-induced changes in serum free-fatty acids was examined. All rats (n=144) were submitted to a treadmill exercise protocol for 14 days. During the first seven days, they were all fed ad libitum with a diet supplemented with capsaicin. Two thirds of rats maintained this diet during the last seven days (capsaicin-diet group) whereas the other rats were pair fed without capsaicin intake (control-diet group). At the end of the protocol, the acute effect of beta-adrenergic blockade (propranolol) on serum free fatty acid concentrations was tested in half of the capsaicin-diet group (propranolol-capsaicin-diet group). A placebo was injected to all other rats, i. e., the other half of rats in the capsaicin-diet group (placebo-capsaicin-diet group) and those in the control-diet group. Epididymal adipose tissue weight was significantly lower in the placebo-capsaicin-diet and propranorol-capsaicin-diet groups than in the control-diet group (p<0.0001). This change was accompanied by a higher level of fasting serum free fatty acids in the placebo-capsaicin-diet group. These results show that under conditions of pair feeding and exercise training, capsaicin intake induces a significant negative energy balance after only one week of treatment. This is associated with an increase in circulating free-fatty acids which is mediated by beta-adrenergic stimulation.