الفهرس 
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Abstract
The present study was designed to evaluate the role of chlorella in modulating aluminum chloride induced neurotoxicity in rats.Ninety rats were randomly divided into 3 groups (30 each), C, Al, and AlCh as follow: group (C) was used as negative control. group (Al) was exposed to a daily concentration of aluminum chloride as 80 mg/l in drinking water to for twelve weeks. group (AlCh)was exposed to both aluminum chloride in a concentration of 80 mg/l in drinking water + chlorella in a concentration of 5% in feedfor twelve weeks. Five rats from each group were sacrificed 2, 4, 6, 8, 10, and 12 weeks post exposure to obtain blood and brain samplesThe measured parameters are:Oxidative stress status (LPO, NO, SOD and GSH), acetylcholine esterase enzyme (AChE) in brain and serum samples, concentration of dopamine in brain tissue, Aluminum level in brain tissue and histopathological investigations of brain tissue.
The result of lipid peroxide levels in brain of aluminum chloride exposed rats revealed a significant increase compared to the control group all over the whole period of the experiment (12 weeks). The comparison between lipid peroxide levels in brain of rats exposed to aluminum and those exposed to both aluminum and chlorella indicated a significant decrease in group exposed to both aluminum and chlorella compared to aluminum group all over the whole period of the experiment except at the fourth week. The same results of lipid peroxide levels in brain were recorded also in serum of both aluminum chloride exposed rats and those exposed to both aluminum chloride and chlorella. The only difference was recorded that no significant decrease in the eighth week in both aluminum chloride + chlorella group in comparison to aluminum chloride exposed group. The results of nitric oxide levels in brain indicated significant increase in aluminum chloride exposed groups except the eighth and twelfth weeks compared to control group. group exposed to both aluminum and chlorella showed a decrease in the level of nitric oxide in brain compared to aluminum chloride exposed group. The previous results were only significant at the fourth and tenth weeks. Nitric oxide levels in serum revealed a significant increase in aluminum chloride exposed group compared to the control group at 4, 6, 8 and 12 weeks. A significant decrease in the level of nitric oxide in serum of aluminum + chlorella compared to aluminum group was recorded at 8, 10 and 12 weeks. The result of superoxide dismutase level in brain indicated a significant increase in aluminum group compared to control group at 4, 6, and 8th week. The group exposed to both aluminum and chlorella showed a significant decrease in SOD level in brain started from the fourth week till the end of the tenth week and a significant increase at the twlfth week. Opposite to the result of SOD in brain, the levels in serum were decreased in the aluminum group compared to the control group at 8, 10 and 12 weeks, and elevated in aluminum chloride + chlorella group at the same time of exposure from the eighth to the twelfth weeks. The result revealed no significant change between aluminum exposed group and the control. A significant decrease was recorded between aluminum + chlorella group and the control group only at the fourth and tenth weeks, also a significant decrease in aluminum + chlorella group was recorded at 4, 10 and 12 weeks compared to aluminum group. Reduced glutathione in serum showed a significant increase in aluminum group at 6, 10 and 12 weeks compared to the control. A significant decrease in GSH was recorded in aluminum and chlorella group compared to aluminum group only at 10 and 12 weeks.
The AchE levels were increased in aluminum chloride group compared to the control group, the only significant increase was recorded at 8 and 10 weeks. In Aauminum + chlorella group the only significant decrease compared to aluminum group was recorded at the eighth week. The results of AchE level in serum showed no sign. Change between aluminum group and the control, the only significant decrease in aluminum + chlorella group compared to aluminum group was recorded at the sixth week.
Estimated levels of dopamine in brain showed a significant decrease in aluminum chloride group only at the 6th and 12th weeks compared to the control group. On the other hand a significant increase was recorded in aluminum + chlorella group compared to aluminum chloride group at the 10th and 12th week.
The result of aluminum concentration in brain revealed a significant increase in aluminum group compared to the control group all over the whole period of the experiment. The level of aluminum in brain of rats exposed to aluminum + chlorella showed a significant increase compared to the control group all over the whole period of the experiment. The recorded levels of aluminum concentration in aluminum + chlorella group were less the aluminum chloride group but not significantly indicated all over the whole period of the experiment.
The histopathological investigation of cerebral cortex showed blood vessels congestion with degenerated neurons, also neuronal necrosis, neuropilevaculation, and focal glia cell reaction in rats exposed to aluminum chloride (Al group). group of rats exposed to both aluminum chloride and chlorella showed mild neuronal degeneration and neuropilevaculation (6th week). At the 8th week neuronal necrosis and mild glia cell reaction were observed. At the end of the experiment (12th week) noral neurons and blood vessels were recorded. Investigation of cerebellum showed degenerated and necrotic purkinji cells (4th and 6th weeks), the necrosis of purkinji cells was severe at the 12th week with increased number of astrocytes in molecular layer in aluminum chloride group (Al group). Cerebellum of rats exposed to both aluminum chloride + chlorella (Alch) showed normal purkinji cells at 12th week. Investigation of the hippocampus of rats exposed to aluminum chloride (Al group) showed necrotic neurons at the 4th, 8th and 12th weeks. The hippocampus of rats exposed to aluminum chloride + chlorella showed necrosed neuron with irregular distribution at the 6th week and normal neurons at 12th week.