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Abstract
Summary
Fish oil as a rich source of omega-3 PUFA has been shown to be a hypolipidemic, anti-inflammatory and antiplatelet agent, and thus it is a cardioprotectant reducing risk factors for coronary heart disease.
Olive oil with its high oleic acid content and abundant polyphenols guard against atherogenesis. Olive oil increase antioxidant capacity in the liver, heart, aorta, platelets and brain. In addition, olive oil has got NO releasing properties.
Melatonin is a potent antioxidant that plays a critical role in free radical scavenging. Melatonin has a hypocholesterolemic effect and thus it has protective effects on the cardiovascular system by reducing risk of atherosclerosis.
This thesis aims at evaluation of the possible protective effects of fish oil, olive oil and melatonin on the induction of hypercholesterolemia in adult male rats. It also aims at study of the effect of the same diet additives on treatment of hypercholesterolemia.
100 rats were used in this study in two experiments (50 rats each).
Experiment I (Duration 10 weeks) : Aims at evaluation of the modulating effects of fish oil, olive oil and melatonin on the parameters of the lipogram and markers of oxidative stress in plasma of rats fed a 1% cholesterol enriched-diet for 10 weeks.
The experiment also included two control groups 10 animals each, a standard diet and a cholesterol enriched diet groups.
Experiment II (Duration 2 weeks) : Aims at evaluation of the beneficial effects of fish oil, olive oil, and melatonin (after cessation of 1% cholesterol feeding for 10 weeks) on the parameters of the lipogram and markers of oxidative stress.
A standard diet group and a cholesterol fed group were also included in Exp. II.
The oils were given in an oral dose of 0.5 ml/day/rat and melatonin in a dose of 75 microgram/day/rat by subcutaneous injection.
Blood samples were taken at the end of each experiment after over night fasting by puncture of the retro-orbital sinus, centrifuged and the serum was frozen at –20 c until processed.
Lipid profile parameters measured were TPC, LDL, TG and HDL.
Markers of oxidative stress assessed were SOD, Total thiol, NO (also a marker of endothelial – cell function) and LP (TBARS).
Histological examination of the aorta was done to assess the presence of atherosclerosis.
Data were collected and statistically analyzed by computer program SPSS (Ver. 11).
The results of this work showed that feeding cholesterol show significant increase in TPC, LDL and TG and lipid peroxide in Exp. I and II, while the levels of HDL, S.O.D, NO and total thiol showed significant decrease.
Exp. I (prevention)
There is a significant decrease in the level of plasma cholesterol, LDL and TG and lipid peroxide by using fish oil, olive oil and melatonin while the levels of S.O.D, NO and total thiol were significantly increased and non significant change in the level of HDL.
Examination of the aorta in Exp. I (prevention) showed the presence of early atheromatous lesion in fish oil and olive oil groups but in melatonin group, the atheromatous lesion was less pronounced.
Exp. II (treatment)
The results of this experiment showed the same modulation (though less) as experiment I as regards the lipogram parameters and oxidative stress markers.
On the other hand histopathological examination of the aorta in Exp. II (treatment) showed atheromatous fibrous plaque in all groups (fish oil, olive oil and melatonin) but absence of well developed fibrous cap which characterize the cholesterol fed control group. The improvement was less in Exp. II than in Exp. I due to the short period (2 weeks only) of the experiment to produce marked change in the aortic wall.