K. ANANTH NARAYAN, JOHN J. MCMULLEN, BUTLER," TROY WAKEFIELD 2 AND WILLIAM Nutrition Group, Microbiology and Nutrition Division, Food Sciences Laboratory, U.S. Army Natick Laboratories, Natick, Massachusetts 01760
DENNIS P. K. CALHOUN
ABSTRACT Adult rats were fed a low fat (4%) or a high fat (40%) diet, and groups of other rats selected for good running were fed these two diets and were treadmill exercised 5 days a week for 6 weeks. The serum triglycérides were signifi cantly lower in exercised rats fed the low fat diet, but not in those fed the high fat diet, as compared with corresponding controls. The liver lipids were vastly elevated in sedentary rats fed the high fat diet as compared with those fed the low fat diet. An interesting effect of exercise was reflected by the near normal liver lipid levels in rats fed the high fat diet and exercised. However, in these animals, the muscle concentration of cholesterol was significantly higher than that in all other groups. The very low density lipoproteins tended to be lower while the low density lipoproteins tended to be greater in exercised as compared with sedentary rats. It was suggested that the decline in very low density lipoproteins was due to decreased synthesis resulting from adaptive changes in the exercised animal. It was further postulated that the increase in low density lipoproteins was possibly due to increased synthesis necessitated by the need to enhance the catabolism and excretion of cholesterol in exercised animals. J. Nutr. 105: 581-587,1975. INDEXING
KEY WORDS
exercise
•lipoproteins
In the development of feeding systems for field feeding of troops, logistical con siderations demand miniaturization of ra tions and food packets. In many instances, this can be easily done by freeze-dehydration and reversible compression.3 In some cases, it is necessary to increase the density of energy in foods by selecting food items with a high fat content. It is, therefore, desirable to evaluate the nutritional effects of high fat foods, especially under condi tions simulating combat stress conditions. Although data are available in the litera ture concerning the changes in liver and serum lipids of rats as a result of treadmill exercise and dietary manipulations ( 1-3 ), little is known about the various density classes of serum lipoproteins of rats under stressful conditions. Such studies are par ticularly relevant when we consider that recent reports from this laboratory * and elsewhere (4) have shown that total serum cholesterol may remain virtually unaltered
•fat levels
•tissue lipids
in spite of drastic, but reciprocal, effects on lipoprotein concentrations. In this report, we have examined the effect of moderate physical exercise and two levels of a fat mixture on rat tissue lipids and serum lipoproteins. MATERIALS
AND METHODS
Seventy male Holtzman rats (340 g) were screened by running 15 minutes/day for 4 days on a treadmill in order to select 20 good runners. Upon selection, they were Received for publication November 1, 1974. 1Presented in part at the 68th Annual Meeting of the Federation of American Societies for Experi mental Biology, Atlantic City, N.J. (1974) Federation Proc. 30, 677. (Abstr.) 2Biological Science Assistant. This work represents partial fulfillment of his military obligation. 3Technical Bulletin (1973) Foods of Tomorrow: Compressed Foods. Food Processing 34, 32-33. «Narayan, K. A.. McMullen, J. J.. Butler, D. P., Wakcfield, T. & Calhoun. W. K. (1973) Serum lipo proteins and liver lipid composition of rats fed a high level of corn oil. Federation Proc. 32, 934. (Abstr.) 581
Downloaded from https://academic.oup.com/jn/article-abstract/105/5/581/4763469 by Washington University in St. Louis user on 19 February 2019
Effect of Exercise on Tissue Lipids and Serum Lipoproteins of Rats Fed Two Levels of Fat1
582
NARAYAN ET AL. TABLE 1 Effect of exercise on serum and liver lipids of rats fed two levels of fat1 Total lipid
Protein
Cholesterol
serumLow
Phospholipid
Triglycéride
mg/ÃŽOOml
fatcontrolHigh 6.6±
9.3±13±1497.166.1(P
fatcontrolLow 4.1±
DENNIS P. K. CALHOUN
ABSTRACT Adult rats were fed a low fat (4%) or a high fat (40%) diet, and groups of other rats selected for good running were fed these two diets and were treadmill exercised 5 days a week for 6 weeks. The serum triglycérides were signifi cantly lower in exercised rats fed the low fat diet, but not in those fed the high fat diet, as compared with corresponding controls. The liver lipids were vastly elevated in sedentary rats fed the high fat diet as compared with those fed the low fat diet. An interesting effect of exercise was reflected by the near normal liver lipid levels in rats fed the high fat diet and exercised. However, in these animals, the muscle concentration of cholesterol was significantly higher than that in all other groups. The very low density lipoproteins tended to be lower while the low density lipoproteins tended to be greater in exercised as compared with sedentary rats. It was suggested that the decline in very low density lipoproteins was due to decreased synthesis resulting from adaptive changes in the exercised animal. It was further postulated that the increase in low density lipoproteins was possibly due to increased synthesis necessitated by the need to enhance the catabolism and excretion of cholesterol in exercised animals. J. Nutr. 105: 581-587,1975. INDEXING
KEY WORDS
exercise
•lipoproteins
In the development of feeding systems for field feeding of troops, logistical con siderations demand miniaturization of ra tions and food packets. In many instances, this can be easily done by freeze-dehydration and reversible compression.3 In some cases, it is necessary to increase the density of energy in foods by selecting food items with a high fat content. It is, therefore, desirable to evaluate the nutritional effects of high fat foods, especially under condi tions simulating combat stress conditions. Although data are available in the litera ture concerning the changes in liver and serum lipids of rats as a result of treadmill exercise and dietary manipulations ( 1-3 ), little is known about the various density classes of serum lipoproteins of rats under stressful conditions. Such studies are par ticularly relevant when we consider that recent reports from this laboratory * and elsewhere (4) have shown that total serum cholesterol may remain virtually unaltered
•fat levels
•tissue lipids
in spite of drastic, but reciprocal, effects on lipoprotein concentrations. In this report, we have examined the effect of moderate physical exercise and two levels of a fat mixture on rat tissue lipids and serum lipoproteins. MATERIALS
AND METHODS
Seventy male Holtzman rats (340 g) were screened by running 15 minutes/day for 4 days on a treadmill in order to select 20 good runners. Upon selection, they were Received for publication November 1, 1974. 1Presented in part at the 68th Annual Meeting of the Federation of American Societies for Experi mental Biology, Atlantic City, N.J. (1974) Federation Proc. 30, 677. (Abstr.) 2Biological Science Assistant. This work represents partial fulfillment of his military obligation. 3Technical Bulletin (1973) Foods of Tomorrow: Compressed Foods. Food Processing 34, 32-33. «Narayan, K. A.. McMullen, J. J.. Butler, D. P., Wakcfield, T. & Calhoun. W. K. (1973) Serum lipo proteins and liver lipid composition of rats fed a high level of corn oil. Federation Proc. 32, 934. (Abstr.) 581
Downloaded from https://academic.oup.com/jn/article-abstract/105/5/581/4763469 by Washington University in St. Louis user on 19 February 2019
Effect of Exercise on Tissue Lipids and Serum Lipoproteins of Rats Fed Two Levels of Fat1
582
NARAYAN ET AL. TABLE 1 Effect of exercise on serum and liver lipids of rats fed two levels of fat1 Total lipid
Protein
Cholesterol
serumLow
Phospholipid
Triglycéride
mg/ÃŽOOml
fatcontrolHigh 6.6±
9.3±13±1497.166.1(P
fatcontrolLow 4.1±
