Summary:
Atherosclerosis is a systematic disease in which patchy deposits of fatty
material (atheromas or atherosclerotic plaques) develop in the walls of
medium-sized and large arteries, leading to reduced or blocked blood flow. The
retina is one of the multiple organs that can be affected.
Age related macular degeneration (ARMD) is the leading cause of irreversible
blindness among older people. Several studies have suggested that increased
dietary fat and cholesterol uptake, as well as oxidative stress may play a
role in the pathogenesis of ARMD. In addition, recent studies have shown that
hypercholesterolemia and lipid metabolism disorders may cause functional,
morphological and ultrastructural changes in the retina such as vacuolation,
thickening and breaks of the bruch’s membrane (BM).
Recent studies have shown a protective effect of various antioxidants, such as
vitamins C and E, flavonoids and multivitamin mineral complexes against retinal
oxidative stress and ultrastructural retinal changes in animal models of
genetic hypercholesterolemia.
The aim of this project is to investigate the potential protective effect of
aqueous extract of crocus sativus stigmas (saffron) in the retina of
apolipoprotein E (apoE)- deficient mice fed a high cholesterol diet. Previous
studies have shown the neuroptotective and anti-ischemic role of crocus
sativus, leading to the hypothesis that crocus sativus (saffron) as a dietary
factor may reduce the effects of hypercholesterolemia in the retina.
Three groups of seven mice each were used. The first one, (control group)
consisted of wild C57bl6 mice which were fed regular mouse chow. The second
group(apo-E) consisted of apoE – deficient mice fed a high cholesterol diet.
Apo E deficient mice is a well studied animal model of atheromatosis. They
develop spontaneously hypercholesterolemia, high LDL blood levels, and
atherosclerotic lesions similar to those developed in the human vascular
system. The third group (apo-E+C) consisted of seven apoE – deficient mice fed
a high cholesterol diet and saffron supplement. In the third group 25mg/kg of
body weight of saffron was administered in drinking water.
After 20 weeks time the animals were sacrificed by euthanasia and the ocular
bulbs were enucleated. For each animal one or two eyes were fixed for
histological analysis in optical microscope.
At the start and at the end of the experiment blood samples were collected for
biochemical analysis of lipidemic profile, oxidative stress and inflammatory
markers. Analysis included total serum cholesterol, serum triglycerides, low
density lipoprotein (LDL), lipid peroxides (perOX), leptin, and C reactive
protein (CRP).
The histological analysis included examination of the retina under optical
microscope, digitizing of the histological images and digital processing of the
images in order to estimate the thickness of the retina and the retinal layers,
as well as the cell density of the outer nuclear layer of the retina.
Statistical analysis was then performed in order to examine correlations that
support the hypothesis of this project.
The results showed that in apo-E+C group the blood glucose levels were similar
to those of control group, while apo-E group had elevated levels. Furthermore,
the body weight of apo-E group was elevated in contrast to
apo-E+C group. The histological analysis showed a lower cell density in outer
nuclear layer ONL, as well as a thinning in ganglion cell layer in apo-E group,
in contrast to apo-E+C group which did not differ significantly from the
control group. These findings lead to the conclusion that Crocus Sativus had a
protective effect against retinal changes due to hypercholesterolemia and it
also reduced the glucose levels and body weight to the corresponding animal
group.
Keywords:
retina, atheromatosis, Crocus Sativus, Apo-E, mice
