الفهرس 
cover englishOnly 14 pages are availabe for public view
 |  | from | 148 |  |  |
| | | from | 148 | | |
Abstract
Aluminum oxide nanoparticles (Al2O3 NPs) have been widely used in vaccine manufacture, drug delivery systems, bone substitutes, food additives, human care products, and cosmetics. However, they also have adverse effects on different organs including the liver, kidneys, and testes. Melatonin has numerous pharmacological effects such as anti-inflammatory, anticancer effects, and antioxidant, particularly against metals by forming melatonin metal complexes. The present study aimed to investigate the protective effects of melatonin against Al2O3 NPs -induced toxicity in the rat brain and spinal cord tissue sections. Forty adult male Wistar rats were allocated to four groups: the untreated control (received standard diet and distilled water), Al2O3 NPs-treated (received 30 mg/kg body weight Al2O3 NPs), melatonin and Al2O3 NPs-treated (received 30 mg/kg body weight Al2O3 NPs + 10 mg/kg body weight melatonin), and melatonin-treated (received 10 mg/kg body weight melatonin) groups. All treatments were administered daily by gastric gavage for 28 days. Then, the rats were sacrificed, and samples from various brain regions (cerebrum, cerebellum, and hippocampus) and spinal cord (gray and white matter) were subjected to biochemical, histopathological, and immunohistochemical analyses. Al2O3 NPs substantially increased malondialdehyde, β-amyloid 1–42 peptide, acetylcholinesterase, and β-secretase-1 expression in brain tissues, whereas they markedly inhibited the glutathione levels in brain tissues. Moreover, they significantly increased malondialdehyde and 8-hydroxydeoxyguanosine and markedly inhibited catalase and superoxide dismutase levels in spinal cord tissues. Furthermore, Al2O3 NPs induced severe histopathological alterations including vacuolation of the neuropil, enlarged pericellular and perivascular spaces, vascular congestion, neuronal degeneration, and pyknosis in different brain areas and gray matter of the spinal cord with also vacuolation, ballooning, and fusion of myelin sheaths with axonal degeneration and sometimes axonal disappearance in the white matter of the spinal cord. Al2O3 NPs treatment also resulted in an intense positive caspase-3 immunostaining in both brain and spinal cord tissues. Conversely, the administration of melatonin alleviated the adverse effects induced by Al2O3 NPs. Therefore, melatonin can ameliorate the neurotoxic effects induced by Al2O3 NPs.