الفهرس 
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Abstract
The aim of the current study was to investigate the neuroprotective effects of MLT against ionizing radiation-induced damage in brain. The rats were randomly allocated into five groups of eight rats each. Body weight was measured at the beginning and every other day throughout the study and the dose of MLT was adjusted accordingly. The rats were anesthetized and the blood samples were collected directly from the heart and then placed in EDTA tube. The plasma was separated and stored at -20 C further biochemical analyses. The brain from each rat was excised immediately and the left portion of the midbrain was fixed in 10% phosphate-buffered formalin for histological studies, while the right portion of each the midbrain was homogenized for biochemical assay. Results were analyzed using GraphPad, Prism, 6.01. Means and the standard error (±SD) were estimated. One-way with Duncan multiple comparison tests was used to estimate the differences between means of different groups. Conclusion: In this study we investigated the radio-protective effect of MLT on brain of rats exposed to 4Gy radiation from cesium-137 source. The exposure to γ- irradiation resulted in a significant biochemical and physiological changes in brain. There was a significant excitotoxic effect marked by imbalance in glutamate/GABA ratio due to increased glutamate release. This is accompanied with decrease in nestin levels in blood of irradiated rats. Moreover, there was increased oxidative stress marked by increased lipid peroxidation and remarkable decrease in the endogenous antioxidants including GSH, GPx. SOD and CAT in brain or irradiated rats. Similarly, there was a significant increase in the levels of pro-inflammatory cytokines including IL-β, IL-6, TNF-α and CRP with a concomitant decrease in the anti-inflammatory cytokine, IL-10. In addition, immunehistochemical study revealed significant increased expressions of P53 and caspase-3 in brain of irradiated rats. Treatment with MLT ameliorated the imbalance in neurotransmitters and protected against glutamate excitotoxicity indicating neuroprotective effects of MLT. The prophylactic effect of MLT was also demonstrated by alleviation of oxidative stress and inflammation marked by decrease in lipid peroxidation and inflammatory cytokines with up-regulation of the integral antioxidants, anti-inflammatory cytokines and CRP in the treated rats. The protective effect of MLT is marked by down-regulation of the expression of P53 and caspase-3 indicating MLT’s antiapoptotic effect. Therefore, the neuroprotective function against radiation exposure is attributed to its multiple properties including of antioxidation, anti-inflammation, antiapoptosis and antiecitotoxicity. These characteristics can improve acute influence of radiation exposure during radiotherapy, occupational industry, and space travel and explorations in highly radiosensitive organs such as brain, gonads and bone marrow. MLT has several favorable properties and can be beneficial in clinical settings after support and confirmation of further investigation on human.