No abstract

A two-factorially experiment was done over a period of 42 days using 32 male, weaned Sprague-Dawley rats in order to study the effect of insufficient protein supplementation, with regard to quantity and quality (13% protein in comparison to 18%, and an essential amino acid index of 64 in comparison to 92%, resp.), on weight development and serum growth hormone concentration. Qualitative protein deficiency had a greater adverse effect on weight development and feed utilization than did quantitative protein deficiency. Both test factors combined brought about the lowest body weight and poorest feed utilization. A lowered hematocrit value occurred only after quantitative protein deficiency. The serum urea concentration was elevated after protein deficiency due to poor quality protein; the serum protein concentration tended toward reduction in both the case of qualitative as well as in the case of qualitative-quantitative protein deficiency. After providing the animals poor quality protein, growth hormone levels in serum were reduced, whereas the concurrence of both factors of protein deficiency caused the growth hormone concentration in serum to rise to a value 4.2-fold of the control value.

We divided 36 male pathogen-free Sprague-Dawley rats with an average live mass (LM) of 51 g into four treatment groups of nine animals each. They received for a period of 28 trial days a semisynthetic purified diet based on casein for ad libitum consumption, supplemented with 5 ppm zinc (groups 1-3) or 57 ppm zinc (group 4) as zinc sulfate. In addition to the diet, groups 2 and 3 were given a diuretic supplement of amiloride at the therapeutic dose rate (0.4 mg amiloride/kg LM0.75 per day) or in a dosage corresponding to the chronic toxicity level (maximum tolerated dose; 0.8 mg amiloride/kg LM0.75 per day). The supplementation with amiloride, acting as a potential Zn-binding ligand at the selected dosage levels, had no influence on the animals' live weight during the 28-day trial period; weight gain was determined solely by the dietary Zn concentration. Amiloride administered at the therapeutic or the maximum tolerated dose produced no evidence of a diminished Zn status in terms of the alkaline phosphatase activity in the serum or the Zn concentration in the serum, femur and testes. Medication with amiloride at the maximum tolerated dose even exerted a positive effect on the zinc supply status as demonstrated by the raised Zn concentration in the serum. This suggests that zinc supplementation may not be required during medication with amiloride in human medicine.

In six groups of nine young Sprague-Dawley rats each, the coconut fat used in the basal diet (group I) was replaced to 60% by pure oleic acid (group II) or linoleic acid (group III), respectively, by 0.6% of alpha-linolenic acid (IV), eicosatrienoic acid (V) and eicosapentaenoic acid (VI). A 60% replacement of the coconut fat in the basal diet by pure oleic acid, respectively, by 0.6% of eicosapentaenoic acid or eicosatrienoic acid significantly decreased the total cholesterol concentration in serum by 21% (HDL -28%; LDL -15%; VLDL -48%), respectively, 19% (HDL -12%; LDL -42%; VLDL +69%) or 15% (HDL -11%; LDL -21%) and the total free cholesterol concentration by 22% (HDL -27%), respectively, 41% (HDL -31%; LDL -66%) or 23% (HDL -21%; LDL -31%). The substitution of the coconut fat by 60% oleic acid or 0.6% alpha-linoleic acid had no influence on the total and total free cholesterol concentration in serum, though in the LDL-fraction a significant decrease of cholesterol could always be found. The concentrations of free fatty acids in serum were not influenced by the unsaturated dietary fatty acids while the phospholipid concentration was reduced by linoleic acid (-15%) and by eicosapentaenoic acid (-18%). The triglyceride content in serum was decreased by linoleic acid (-29%) and by eicosatrienoic acid (-25%).

In an earlier Zn-deficiency experiment (8) pair-fed-control rats surprisingly showed a 100% increased osmotic fragility of erythrocytes against hypotonic sodium chloride solutions. Because coconut fat, which is very low in essential fatty acids, was used, a deficiency of essential fatty acids was assumed. When the experiment was repeated the diet's coconut fat was replaced by sunflower oil (21% oleic acid, 69% linoleic acid). The erythrocytes of the animals with Zn-deficiency showed an increase in osmotic fragility as against the control groups fed ad libitum. The data of the pair-fed control animals was in between those two groups and did not differ from the other two groups. Using sunflower oil instead of coconut fat decreased the osmotic fragility of the pair-fed animal's erythrocytes in opposition to the preceding experiment up to 100%. Additional Ca deficiency increased the osmotic fragility of the erythrocytes significantly in all three groups. When the Zn and Ca deficiency animals were repleted over 5 days on the basic diet the osmotic fragility of the erythrocytes was decreased significantly. The results show that the use of coconut fat in a restrictive diet causes essential fatty-acid deficiency. It ist also shown that the osmotic fragility of the erythrocytes depends partially on the status of Zn in dietary fat as well.