Evaluation of differential effects of carbohydrate and fat intake on weight gain, serum IGF-1 and erythrocyte Na+K+ATPase activity in suboptimal nutrition in rats.
OBJECTIVE
Suboptimal nutrition leads to growth delay, frequently without over clinical or biochemical signs. We hypothesize that changes in serum IFG-1 and erythrocyte sodium-potassium ATPase activity (ENKA) may be indices of suboptimal nutrition.


METHODS
Male Sprague-Dawley rats were pair-fed for 4 weeks with balanced diets of different carbohydrate (CHO) to fat (FAT) ratios (3:1, 2:1, and 1:1) and three levels of energy intake (ad-libitum, 80%, and 60%), corrected for actual body weight). Daily weight gain and weekly tail growth were monitored while ENKA, serum total protein, T3, insulin and IGF-1 were measured after four weeks. Refeeding experiments were also performed with the 3:1 and 1:1 CHO:FAT diets, including 4 weeks of dietary restriction and one week of ad-libitum feeding.


RESULTS
Weight gain, tail growth, and IGF-1 decreased (p < 0.05) in all groups after 1 week of dietary restriction. A decrease in ENKA (p < 0.05) was found in rats that consumed 60% of ad-libitum energy intake only after 4 weeks. At the end of dietary treatment, weight gain was higher (p < 0.05) in rats fed the 3:1 CHO:FAT diet. In contrast, when energy was restricted to 80% or 60% of ad-libitum intake, rats fed the 1:1 CHO:FAT diet gained more weight (p < 0.05) compared to the 3:1 and 2:1 CHO:FAT diets. After 1 week of refeeding body weight, tail growth and ENKA returned to control values while serum IGF-1 levels remained depressed.


CONCLUSIONS
Acute nutritional changes are clearly detected by a reduction of serum IGF-1 while ENKA may be a useful index for assessing chronic suboptimal nutrition.
Tarim
O
O
Department of Pediatrics, Maimonides Medical Center, Brooklyn, New York, USA.
Chasalow
F I
FI
Murphy
J
J
Rising
R
R
Carrillo
A
A
Lifshitz
F
F
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology*; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology*; D002149:Energy Intake; D004912:Erythrocytes / Q000201:enzymology*; D005069:Evaluation Studies as Topic; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*; D015430:Weight Gain
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D007334:Insulin-Like Growth Factor I; D000254:Sodium-Potassium-Exchanging ATPase