Effect of aluminum chloride on the hippocampus of adult ratsand the possible protective role of Nigella sativa: a histologicaland immunohistochemical study

BackgroundAluminum is among the most abundant elements on earth and it is associated withthe etiology of Alzheimer’s disease. The hippocampus plays an important role inshort-term memory and decision making. The Nigella sativa was reported to haveanti-inflammatory and antioxidant properties.Aim of the workTo investigate the histopathological effects of aluminum chloride on the hippocampusof adult male albino rat and the possible protective role of N. sativa.Materials and methodsTwenty-five adult male albino rats were used in this study. They were divided intofive groups (each group included five rats): group I (control) received no treatmentand group II (N. sativa treated) received N. sativa oil daily at a dose of 1 ml/kgorally for 8 weeks. Group III (aluminum chloride treated) received aluminum chloridedaily at a dose of 320 mg/kg/l added to the drinking water for 8 weeks. Group IV(aluminum chloride+N. sativa) received N. sativa oil with aluminum for 8 weeksat the same dose as the two previous groups. Group V (withdrawal) receivedaluminum only without N. sativa oil at the same previous dose for 8 weeks andthen the animals were left without treatment for another 4 weeks. Specimensfrom the hippocampus were processed for light and electron microscopicalexamination. Also, the immunohistochemical technique was used with glialfibrillary acidic protein (GFAP).ResultsGroup III showed apoptotic changes in many pyramidal cells. Moreover, therewas a significant decrease in the number of pyramidal cells. These changes wereaccompanied by a significant increase in GFAP-positive astrocytes. In group IV,minimal apoptotic changes were detected in pyramidal cells, with a significantincrease in their number. This was accompanied by a significant decrease in GFAPpositiveastrocytes. In group V, many pyramidal cells still showed degenerativechanges, with a significant decrease in their number. GFAP-positive cells showed asignificant increase. Gliosis was marked in the pyramidal cell layer.ConclusionOne-month withdrawal of aluminum chloride was not sufficient to gain a normalhistological appearance of the hippocampus. N. sativa could be used to protect thehippocampus against aluminum chloride-induced damage.