Effects of Feeding Periods of High Cholesterol and Saturated Fat Diet on Blood Biochemistry and Hydroxyproline Fractions in Rabbits

Hypercholesterolemia and hypertriglyceridemia are considered as important risk factors during the atherosclerotic process. The aim of the present investigation was to study the total cholesterol (TC), low-density lipoprotein cholesterol (LDLC), high density lipoprotein (HDL), triglyceride (TG), platelet levels and hydroxyproline fractions during the pathogenesis of atherosclerosis. For this purpose, twenty five 12-weeks, New Zealand white male rabbits, were purchased, individually caged, and divided into either control group or cholesterol-fed group. The control group (n = 10) was fed 100 g/day of normal diet, ORC-4 (Oriental Yeast Co. Ltd., Tokyo, Japan) for a period of 15 weeks. The cholesterol-fed group (n = 15) was fed a high cholesterol and saturated fat diet of ORC-4 containing 1% cholesterol plus 1% olive oil (100 g/day) for periods of 5 (group 1), 10 (group 2) and 15 (group 3) weeks. Blood sample from each animal was taken at the end of the experimental period for the biochemical analysis. The results of the present study showed that TC, LDLC, TG, HDLC and platelets were significantly (P < 0.01) increased in cholesterol-fed rabbits as compared with control rabbits. The serum hydroxyproline (Hyp) in rabbits belonging to group 1 showed no significant alteration when compared to control group. Group 2 rabbits showed a significant increase of 103% (P < 0.01) and 100% (P < 0.001) in free and protein-bound hydroxyproline fractions respectively when compared to control rabbits. However, there was no significant change in peptide-bound and total serum hydroxyproline levels as compared to the control group (P > 0.05). There was no significant (P > 0.05) decrease of free serum hydroxyproline in group 3 rabbits when compared to control rabbits. On the other hand, group 3 rabbits showed a significant increase in peptide-bound and protein-bound Hyp by 517% (P < 0.05) and 100% (P < 0.01) respectively when compared to control rabbits. However, total serum Hyp in group 3 rabbits showed no significant (P > 0.05) change when compared to control rabbits. These results suggest that feeding rabbits high cholesterol and saturated fat diet for feeding periods of 5, 10 and 15 weeks induced significant change in TC, LDLC, HDL, TG, platelet levels and various Hyp fractions in serum without any significant change in the total Hyp content.