الفهرس 
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Abstract
Cypermethrin (CP), a class II of pyrethroids, is used in agriculture to control ectoparasites that infect cattle, sheep, and poultry. The extensive use of CP in many fields aims to improve the quality of crops and prevent pests away from crops, however it shows risk to human health and environment. CP can cross the blood brain barrier (BBB) to exert neurotoxicity in the CNS and also induces motor deficits. Signs for CP-induced neurotoxicity includes its potential epileptic activity and behavioral anomalies in both humans and rats chronically exposed to CP.
CP undergoes hepatic metabolism through hydrolysis and oxidative pathways by the CP-450 enzymes to yield reactive oxygen species (ROS), which leads to development of oxidative stress in mammals. ROS directly damage the cellular biomolecules such as lipids, proteins and DNA and consequently lead to cell apoptosis. Sodium channels have been identified as a main target of CP neurotoxicity. CP causes the opening of these channels resulting in prolongation of sodium current subsequently leadsto hyperexcitation of the CNS. This leads to disturbance in sodium current leading to alteration of level μ-amino butyric acid (GABA). Brain damage caused by administration of CP is due to direct or indirect activation of microglia. Microglia activation upregulates various proinflammatory cytokines including interleukin-1(IL-β1) , tumor necrosis factor alpha (TNF-α) and down regulates anti-inflammatory cytokines.
Selenium is an essential micronutrient and considered as a constituent of glutathione peroxidise. It is also crucial for the catalytic activity of a main antioxidant enzyme; thioredoxin reductase. Several reports illustrated the beneficial role of selenium against various toxic compounds on different organs.Selenium shows both an antioxidant and anti-inflammatory activity; however, it also displayed a marked toxicity on different organs especially on the liver. To overcome the toxicity of Selenium, nanotechnology was applied to develop nanometer particulates with large surface area, high surface activity, high catalytic efficiency, strong adsorbing ability and low toxicity.
According to the biological activities of Nano-Se which act as antioxidant and anti-inflammatory, the current study aimed to investigate the possible protective effect of Nano-Se against neurotoxicity induced by cypermethrin in rats.
This was achieved by:
1. Studying their effects on behavioral and histological patterns.
2. Measuring some oxidative stress markers (MDA, GSH).
3. Investigating the effect of Nano-Se on liver enzyme.
4. Assessment of the levels of GABA.
5. Estimation of the levels TNF-α and IL-1β as markers for inflammatory.
The present study was carried out on twenty-four adult male Wistar rats weighing 140±10g.After one week of acclimatization rats were randomly divided into three groups, eight animals in each group as follows:
1. Control (C) group:rats received only standard diet and tap water.
2. Cypermethrin (CP) group: rats were orally given CP (1 mg/kg b.w) with gastric tube for 21 days.
3. Cypermethrin (CP) + Nano-Selenium(Nano-Se)group: rats were orally given CPat dose of 1 mg/kg b.w plus Nano-Se at dose of 2.5 mg/kg b.wby stomach gavage once a day 3 times a week for 3 weeks.
At the end of the experiment period , rats were anesthetized with acute injection of ketamine(80 mg/kg, i.p), and blood was collected by cardiac puncture into non-heparinized tubes and then centrifuged at 3000 rpm for 15 min. Sera were carefully separated and each sample was put in clean cup tube, labeled and kept at – 20oC until biochemical analysis.
• Cypermethrin caused a clear change in the behavior of rats, but the Nano-Se group was observed to be almost normal.
• We also note that theCP has increased liver enzymes as well as bilirubin and there was a decrease in albumin and protein group.
• Cypermethrin decreased the level of GABA in the brain, while rats treated with Nano-Se revealed increase in GABA level that almost returned to the normal level.
• Rats given CP showed signs of inflammation in the brain tissue.
• Cypermethrin revealed the highest oxidative stress factors; as glutathione decreased and peroxidation increased in brain tissue, while Nano-Se increased glutathione and decreased peroxidation in normal brain tissue.
• After having a picture of the brain tissue, it was noted that theCP has caused a shrinking and pale color of the pyramidal cells in the cerebral cortex as well as in the layers of Hippocampus, but the rats treated with Nano-Se were found to have stability and less shrinking brain pyramidal cells.
from the previous results, we conclude the following:
• The Nano-Se protects against the CP-induced neurotoxicity.
• It also protects the liver from harmful effects resulting from CP.
• We suggest the use of Nano-Se to protectagainst the toxicity of CP