Effects of dietary tyrosine on serum cholesterol fractions in rats

Abstract

The present study was undertaken to measure the effects of dietary tyrosine added to rat diet on serum cholesterol levels in the rat. A total of twenty Wistar strain albino rats were fed with different doses of tyrosine enriched diets containing 0.8 g/100 g, 1.0 g/100 g and 1.2 g/100 g. After 3 weeks of experimental feeding, there was significant increase (p<0.05) in total postprandial serum cholesterol of rats fed with graded of tyrosine when compared with the normal control. Same trend was followed in the week 2 of the same feeding pattern. The effects of dietary tyrosine supplementation on cholesterol levels of the high density lipoprotein (HDL) fraction were comparable, but not all significant on the week 3 treatment. However, there was significant decrease (p<0.05) in week 2 of rats fed with the different graded doses of the tyrosine meal when compared with the normal control group. In addition, significant increase was also observed in the low density lipoprotein (LDL) as compared to the control after week 2 and 3 of tyrosine meal treatment. These results revealed that tyrosine supplementation in a physiological amount may increase cholesterol levels in the rat when added to diet, with a slow release of tyrosine during digestion.

Biochemical changes associated with the administration of aqueous pulp extract of Irvingia gabonensis fruit on adult male Wistar rats

“…The lipid profile result (Table 3) showed a moderate attenuating effect on the serum total cholesterol, LDL, VLDL levels, and subsequently a significant increase in serum HDL in the male albino rats. The potential effects of the extract on the lipid profile may be associated with the decline in the synthesis of cholesterol and its metabolism, as well as the expression of signal receptors of LDL [37]. LDL plays a major role in the development of atherosclerosis, especially after their oxidation while HDL reverses cholesterol transport and transfer of cholesterol esters from cell membranes which free cholesterol to the core of the HDL and inhibits the oxidation of LDL [2,21].…”