الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The oral cavity is underlined by a mucosal membrane and is always moistened by the saliva secreted by the associated major and minor salivary glands. Major salivary glands in humans as well as mice and rats are composed of three pairs of macroscopic glandular organs: parotid, sublingual, and submandibular glands. The submandibular glands are major salivary glands that produce around 60–67% of the total volume of saliva. Saliva has an important role in keeping healthy condition of the oral cavity.
Methotrexate (MTX) is a folic acid antagonist that inhibits cellular reproduction by causing an acute intracellular deficiency of folate coenzymes. Initially used as an anti-neoplastic drug, MTX has been shown to be an effective anti-inflammatory agent, and is now widely used for non-neoplastic inflammatory conditions including psoriasis, inflammatory bowel diseases, vasculitis, ectopic pregnancy and, most commonly, rheumatoid arthritis (RA). However, discontinuation of methotrexate is common due to occurrence of its adverse side effects.
It was revealed that the systemic oxidative stress is an important factor in methotrexate induced toxicity. Methotrexate leads to a reduction in antioxidant enzymatic defense capacity and causes lipid peroxidation. Therefore the antioxidants protect against the oxidative stress and prevent damage of the cell.
Natural herbs and its compounds which are present in the human diet have attracted extensive attention as chemopreventive and protective agents. In this study, selective green tea extract was used. Green tea contains good medical properties, associated with health benefits against multiple diseases including cancer, inflammation, atherosclerosis and cardiovascular disorders and act as antioxidants.
This work was designed to focus on the histological changes induced by Methotrexate on the submandibular salivary gland of adult male albino rats and to clarify the possible protective effect of green tea extracts.
Summary and conclusion
154
Materials and Methods:
Fourty eight adult male albino rats weighing 180-220 gm\each were used in the present study. The animals were randomly divided into four groups as follows:
group I (control group): included 8 animals, they were used as control group.
group II (green tea extract-treated group): included 8 animals that were received 20mg\kg body weight of green tea extract orally twice daily by intragastric gavage needle for four weeks.
group III (methotrexate-treated group): included 16 animals. They were administrated MTX at 2 different doses once weekly for 4 weeks by intraperitoneal route. They were divided into 2 subgroups:
Subgroup IIIa (low dose methotrexate-treated group):
It was composed of 8 rats that were received 2mg\kg body weight of methotrexate by intraperitoneal route once weekly for four weeks.
Subgroup IIIb (high dose methotrexate-treated group):
It was composed of 8 rats that were received methotrexate at a dose 20mg\kg body weight by intraperitoneal route once weekly for four weeks.
group IV (methotrexate and green tea-treated group): included 16 animals. They were given methotrexate at 2 different doses once weekly for 4 weeks together with green tea extract twice daily for four weeks they were divided into 2 subgroups:
Summary and conclusion
155
Subgroup IVa (low dose methotrexate and green tea extract-treated group):
It was composed of 8 rats that were received 2mg\kg body weight Methotrexate by intraperitoneal route once weekly , and 20mg\kg body weight of green tea extract orally twice daily by intragastric gavage needle for four weeks.
Subgroup IVb (high dose methotrexate and green tea extract- treated group):
It was composed of 8 rats that were recieved 20mg\kg body weight Methotrexate by intraperitoneal route once weekly and 20mg\kg body weight of green tea extract orally twice daily by intragastric gavage needle for four weeks.
The general condition and the behavior of the rats were observed. At the end of the study (4 weeks), the animals from all groups were anaesthetized using ether inhalation then were sacrificed. Both submandibular glands of each animal were excised . Half of the glands were fixed in 10% formal saline for light microscopy (L\M) and the other half were fixed in 1% glutaraldehyde in phosphate buffer for Electron Microscopic Study (E\M).
Results and conclusion:
Macroscopic results
The submandibular glands obtained from rats of control group (group I), were large, irregular and lobulated. The submandibular glands of green tea extract-treated group (group II), were apparently similar to those from control group, while the submandibular glands taken from rats either treated with methotrexate (group III) or treated with high dose methotrexate and green tea extract (group IVb) were apparently much smaller in size compared to control group.