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KMID : 1134820000290030471
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Journal of the Korean Society of Food Science and Nutrition
2000 Volume.29 No. 3 p.471 ~ p.478
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Effects of Fasting - refeeding on Rat Adipose Tissue Lipoprotein Lipase Activity and Lipogenesis : Influence of Food Restriction during Refeeding
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Lee Jae-Joon
Choi Byeong-Dae
Chung Chung-Soo
Kim Jin-Geol
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Abstract
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The current study was undertaken to determine the prolonged effects of fasting-refeeding on the lipoprotein lipase (LPL) activity and lipogenesis of adipose tissue in male Sprague-Dawley rats and to investigate the effects of various degrees of food restriction during refeeding on the LPL activity and lipogenesis. The control group (n=5) was fed ad libitum and killed in the fed state at the beginning of the experiment. All rats except control group were fasted for 2 days (n=50). Five rats were killed at the end of fasting and others (n=45) were refed either ad libitum (ad libitum group) or mildly restricted (20% food restricted group), or severely restricted diet (40% food restricted group). Rats were killed on the day of 7th, 14th, and 21st of refeeding. Lipogenesis was determined by the amount of glucose converted to the total lipid. Body weight and epididymal adipose tissue weight returned to control states by 5 days in ad libitum group and by 14 days in 20% food restricted group. As expected, in 40% food restriction during refeeding weight and epididymal adipose tissue weight did not return to control states until day 21. On day 21 after refeeding, the serum total cholesterol concentration of ad libitum group was significantly (p<0.05) higher than that of control group. The serum HDL-C concentration of 40% food restricted group during refeeding was significantly (p<0.05) higher than that of control group. However, there were no significant dif- ferences in serum HDL-C/total cholesterol (TC) ratio and triglyceride concentration among the groups. Fasting for 2 days decreased lipogenesis and LPL activity (p<0.05). On day 21 after refeeding, the lipogenesis of ad libitum group was significantly (p<0.05) lower than that of control group. The lipogenesis of 40% food restricted group during refeeding was significantly (p<0.05) higher than that of control group. Ad libitum group and 20% food restricted group during refeeding allowed heparin-releasable (HR) LPL or total extractable (TE) LPL activity to return to control states. 40% food restricted group during refeeding delayed the return of HR-LPL or TE-LPL activity to return to control states until day 21 of refeeding. These results suggest that food restriction during refeeding can partially or completely prevent the overshoot of LPL activity, and this may influence the rate of lipid accumulation in adipose tissue during refeeding.
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KEYWORD
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fasting-refeeding , food restriction , lipogenesis , lipoprotein lipase
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