SummaryThe present study was undertaken to determine whether the timing of sucrose meal feeding relative to periods of physical activity affects plasma triacylglycerol (TG) levels in rats. Animals were daily meal fed on a basal diet and a 35% sucrose diet for 10 weeks. Meal times were at 08.00-09.00 hr and 21.00-22.00hr. Voluntary running in wheels was allowed between 22.00-08.00hr, but was restricted from 08.00 to 22.00hr. The sucrose diet was given at the morning meal time to one group (M-S eaters) and at the evening meal time to another group (E-S eaters). The timing of the sucrose meal did not have any influence on consumption of either of the two diets, physical activity, weight gain, or the weight of several organs and tissues. Plasma TG, however, was significantly higher in the M-S eaters than in the E-S eaters. Lipoprotein lipase activity of several tissues was not affected by the timing of the sucrose meal. The Triton-induced increase in fasting plasma TG was significantly higher after the sucrose meal than after the basal meal regardless of the timing of the sucrose diet. The TG accumulation rate during the physically inactive period was significantly greater in the M-S eaters than in the E-S eaters, while during the physically active period it was equal in both groups. These results suggest that the effect of sucrose feeding on plasma TG may be conditioned by the timing of sucrose feeding and rats' physical activity.

SummaryThe effect of voluntary wheel-running to modulate sucrose induced hypertriacylglycerolemia was investigated on both sedentary and exercised rats in relation to the timing of sucrose feeding. The exercised group was allowed voluntary wheel-running between 21.00-08.00. Rats of both groups were daily meal-fed a 35% sucrose diet at 20.00-21.00 and a basal diet at 08.00-09.00, or inversely meal fed the two diets at the reversed time for 7 weeks each. At the end of the feeding period, plasma or serum triacylglycerol (TG) levels of exercised rats, as compared to sedentary rats, showed smaller diurnal changes regardless of the timing of sucrose feeding. Hepatic-intestinal TG secretion rates measured during both resting and physically active periods were lower in the exercised rats than in the sedentary control rats, whereas the cardiac and adipose tissue lipoprotein lipase activity of the two groups was not significantly different. These results suggest that voluntary wheel-running exercise may modulate the hypertriacylglycerolemic effect of sucrose in rats regardless of the timing of sucrose feeding, with decreased TG secretion. Key Words voluntary wheel-running, timing of sucrose feeding, plasma and serum TG, TG secretion, lipoprotein lipase, rat It is well known that exercise is useful to lower increased plasma TG con centrations, Sucrose feeding, on the other hand, is believed to elevate plasma TG levels. Hebert et al. (1) and Zavaroni et al. (2) have reported that this hyper triacylglycerolemic effect of sucrose was effectively inhibited by voluntary wheel running in rats when ad libitum-fed on a 63% (w/w) sucrose diet for 10 weeks or a 66% (as percent age of total calories) sucrose diet for 10days. However, using a feeding system which controls the time of meal feeding and voluntary wheel running, our recent laboratory tests have demonstrated that the sucrose feeding related to physical activity influences the plasma TG levels in rats (3). Therefore, it

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