الفهرس 
ABSTRACT
Nanoparticles and nanotechnologyOnly 14 pages are availabe for public view
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Abstract
Regarding fast development of the nanotechnology and its diverse applications including fish medicine, it is very important to have enough data on it’s probably side effects on fish. There for, current study aimed to evaluate the alterations induced by Magnesium Oxide Nanoparticles (MgO NPs) in Nile tilapia, Oreochromis niloticus. One hundred and fifty fish weighing between 70-100g of both sexes were collected from the River Nile at Assiut Governorate. Seventy five fish were intraperitonealy injected (5 fish per group) with different doses of MgO NPs as 0, 200, 400, 600, 800 µg/g fish for determination of 96h LD50. Three replicates were used for each concentration. The 96h - LD50 value was 582 µg/g fish. Another seventy five fish (5 fish / group in three replicate for each group) were intraperitonealy injected with 5%, 20%, 50% and 75% of MgO NPs LD50. Fish samples were taken from each group after 2, 4, 7, 14 and 21 days post injection. At each sampling time, blood and tissue samples were collected and biochemical analyses of serum and homogenates were performed. Tissue samples were also taken for investigation of histological changes of gills, liver, kidney, spleen and brain. Statistical data analysis for the results of total protein and its fractions revealed that: a significant decrease (P<0.05) in total protein and albumin values in fish serum after 2, 4 and 7 days post treatment in groups exposed to 50% and 75% of LD50 when compared with either control, 5% or 20% of MgO NPs LD50. Also, significant decrease in total protein was noticed 14 and 21 days following injection of 20% of MgO NPs LD50 in comparison with 2 and 4 days in the same dose. There was a significant decrease of globulin level 14 and 21 days post injection of 50% of MgO NPs LD50 in comparison with control, 5% or 20% of MgO NPs LD50. The present study declared that Alkaline Phosphatase (ALP) level as indicator of cytotoxicity significantly increased in serum (P<0.05) following the intraperitoneal injection with all doses of MgO NPs Nanoparticles after 14 and 21 days in comparison with the control group. The evaluation of kidney function relies on the measurement of the concentration of serum creatinine, which is affected by the degree of liver disease. The present study showed that there was a significant increase in the level of creatinine in MgO NPs high doses exposed groups (50% and 75% of 96h-LD50 after 2 days but, the level decreased after 14 and 21 days following exposure to 20% and 75% of 96h- LD50 of MgO NPs treated group. Glutathione Peroxidase (GPx) an important antioxidant enzyme, have shown a statistically significant increase (p<0.05) following exposure to 50% and 75% of 96h- LD50 in comparison with control, 5% or 20% of 96h- LD50 of MgO NPs. A significant increase in Nitric Oxide (NO) level in supernatant of homogenized liver of fish exposed to 5% of 96h-LD50 of MgO NPs after 21 days in comparison with 2, 4, 7 or 14 days post exposure to nanoparticles. Histopathological changes correlated well with the the biochemical and other alterations induced by nanoparticles. Gills, displayed congestion in primary lamellae which also extended to the secondary lamellae, and reached the gill arch. Epithelial hyperplasia of primary lamellae and fusion of secondary lamellae increased with increasing dose and time post treatment. Edema of gill arch was observed at high doses and accompanied with hemorrhage which was time dependant. Sloughing of secondary lamellae appeared at high doses after 21 days post treatment. Liver exhibited vacuolar degeneration of hepatocytes with periductal and intralobular inflammatory cells infiltration that was dose and time dependant. Activation of melanomacrophages was also recorded in hepatopancrease. Sever hemorrhage was observed around central vein of liver with zonal coagulative necrosis of hepatocytes. Diffuse Fatty degeneration was also noticed at 4, 7, 14 days post treatment. Thrombus formation was observed in hepatopancrease, portal veins and in central vein at all doses and times of exposure. Kidney showed per vascular hemorrhages and zonal to diffuse vacuolar degeneration at 50% and 75% of 96h- LD50 of MgO NPs. Congestion of glomeruli increased in its level with increasing dose (dose dependant). Diffuse interstitial inflammatory cell infiltration was observed between glomeruli and around blood vessels at all doses and increased with increasing dose. Hypercellularity of glomeruli occurred at high doses. Spleen displayed marked activation of melanomacrophages centers from the lowest dose then continued during the whole period of exposure. There was an opposite relation between hyperplasia of lymphoid follicles and congestion of red pulp of spleen. Thrombosis in blood vessels of spleen was observed in a mild degree in fish exposed to all doses of MgO NPs. Depletion of lymphocytes started to be noticed at high doses 50% and 75% of 96h- LD50 of MgO NPs in a high degree. In Brain, there was congestion in blood vessels of cerebellum. chromatolysis in Purkinje cells with vacuolation and demylination was recorded at all doses and increased with time of exposure. Shrinkage of Purkinje cell layer in cerebellum increased with increasing dose (dose - dependent).