الفهرس 
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Abstract
Ionizing radiations are widely used for treatment of cancer. However, one of the
limitations of using radiation is its toxic effects on normal tissues. Radiation damage to normal
tissues can be partially reduced by the use of radioprotectors that scavenge free radicals
produced during irradiation.
Recently, interest has increased in the development of potential drugs of plant origin
for the modification of radiation effects and have an advantage over the synthetic compounds
in terms of low/no toxicity and with minimum side effects.
Green tea is a potent antioxidant that has attracted considerable attention for its role in
preventing oxidative stress related diseases including cancers, cardiovascular diseases and
fibrosis.
The present study has been undertaken to evaluate the protective effect of GTE against
radiation induced biochemical, hematological and histopathological alterations in Swiss albino
mice. Similar studies were also performed on tumor-bearing mice. This study was achieved
using 80 normal male Swiss albino mice (Group A) and 64 Ehrlich solid tumor-bearing mice
(Group B). Mice in both groups were subdivided into four subgroups, the first subgroup was
considered the control, the second received 1.5% GTE for 14 days, the third received tap water
then exposed to 4 Gy gamma radiation and the fourth subgroup received the same dose of
GTE, then exposed to 4 Gy gamma radiation 30 mins after the last dose. Blood and liver from
groups A and B groups and tumor from group B were collected 24 hours, 3 days and 5 days
post-irradiation to measure the following parameters: hepatic and tumor MDA, hepatic and
tumor SOD, serum aminotransferases, Hb concentration, RBCs, leukocytes, and platelets
counts in addition to histopatholgical examination of liver and tumor tissues.
In normal animals (Group A), exposure to γ radiation lead to significant elevation in
hepatic MDA and decreased activity of hepatic SOD indicating the extensive damage caused
by radiation and the limited capacity of liver to compensate this damage. Gamma irradiation
also caused a significant increase in the serum levels of ALT and AST which indicates the
increased permeability, damage or necrosis of hepatocytes. GTE supplementation prior to
irradiation lead to significantly decreased hepatic MDA level, stimulated the hepatic
antioxidant enzyme SOD activity, and decreased the serum activities of ALT and AST when
comparing their levels in the irradiated only mice showing that GTE to some extant preserved
the structural integrity of liver against radiation induced damage.
Exposing animals to 4 Gy γ radiation lead to severe consequences on the cellular level.
The electron microscopic examination of hepatocytes showed swelling and destruction of
subcellular organelles and aggregation and clumping of nuclear material. However, the
supplementation with GTE led to protection and regeneration of cell organelles as well as
preserving the normal architecture of hepatocyte nuclei.
Whole-body irradiation was found to cause a significant decline in the hematological
constituents in blood of irradiated animals including Hb, RBCs, WBCs and platelets. This can
be due to a direct destruction of mature circulating cells, loss of cells from the circulation by
Summary and Conclusion 109
hemorrhage, or leakage through capillary walls and loss of production of cells. However, the
levels of these hematological parameters were significantly higher in the GTE pretreated
group as compared to irradiated alone animals. These results nominate GTE to be a good agent
to attenuate radiation induced damage to the blood system.
In tumor bearing mice (Group B), the liver was found to be more susceptible to
damage due to tumor burden and irradiated. Significantly high levels of lipid peroxides were
generated in the liver after exposure to radiation. It was accompanied with declined levels of
hepatic SOD indicating the state of oxidative stress experienced by the liver as a distant organ
in tumor-bearing mice. Liver function test were used for further assessment of liver function
and as expected, a significant elevation in the levels of serum aminotransferases was observed
in the irradiated group. Supplementation with green tea extract prior to gamma radiation
exposure lead to significant protection of normal liver tissue from the damage induced by
tumor burden as well as irradiation. This protection is represented by decreased level of lipid
peroxides, enhanced SOD activity, and deceased serum levels of aminotransferases.
The biochemical studies on tumor tissue revealed that GTE exerted no significant
effect on tumor oxidative status. However, the histopathological examination of the tumor
tissue revealed that GTE supplementation resulted in the presence of massive areas of necrosis
in tumor cells with reducing in tumor size either before or after irradiation which implies an
effective role of GTE in improving tumor response to radiotherapy. This could lead us to
conclude that GTE exerts a preferential protection to normal cells in comparison to the tumor
cells and can be used as an adjuvant with radiotherapy.