A highly significant negative correlation (r= -0.981, p< 0.001) between the amount of oyster mushroom (Pleurotus ostreatus) in the diet and cholesterol levels in the serum has been found in male Wistar rats fed shortly after weaning by a a diet with 0.3 % cholesterol. The addition of 1.0, 2.5 and 5.0 % of oyster mushroom to the diet reduced the levels of serum cholesterol by 11, 31 and 46 %, respectively. The diet containing 5 % of oyster mushroom suppressed cholesterol accumulation in the liver and increased the fraction of cholesterol carried by high-density lipoproteins.
Male weaning rats were put on a diet with a physiological nutrient combination adjusted for age, milk casein (E7N = 0.79) and wheat gluten (E/M = 0.30) being the sources of protein. The net protein ratio (NPR) was evaluated weekly until 140 days of age. On days 70 and 140, L-((J-14C)-tyrosine was administered intraperitoneally and 12 h later specific tyrosine activity was determined in the protein fraction of liver and muscle by measuring the incorporation of the labeled amino acid in order to assess protein synthesis over the corresponding time period. Regression lines describing the relationship between animals' weight, age and protein source suggested that the daily weight increase was 6.99 g between days 30-77, 2.97 g between days 77-105 and 0.64 g between days 105-140. Muscle tyrosine levels in rapidly growing animals aged 70 days were 91.0 /¿g/g/12 h for casein and 65.6/ig/g/12 h for gluten. Liver tyrosine levels were 336.4 and 189.6 /rg/g/12 h, respectively. The differences observed at this age were highly significant. In adult animals (140 days old) there were non-significant differences between tyrosine levels in the casein- and gluten-fed groups. The isotope study clearly showed that protein synthesis was reduced in growing and developing animals on vegetable nutrition, which is deficient in essential amino acids, (especially the limiting amino acid lysine, crucial for the utilization of all other amino acids in peptide chain synthesis). The low rate of amino acid utilization found in animals younger than 105 days is consistent with the findings obtained by the isotope method.