Effect of aluminum chloride on the hippocampus of adult rats and the possible protective role of Nigella sativa: a histological and immunohistochemical study

ABSTRACT

Aluminum is among the most abundant elements on earth and it is associated with the etiology of Alzheimer's disease. The hippocampus plays an important role in short-term memory and decision making. The Nigella sativa was reported to have anti-inflammatory and antioxidant properties. To investigate the histopathological effects of aluminum chloride on the hippocampus of adult male albino rat and the possible protective role of N. sativa. Twenty-five adult male albino rats were used in this study. They were divided into five groups [each group included five rats] group I [control] received no treatment and group II [N. sativatreated] received N. sativa oil daily at a dose of 1 ml/kg orally for 8 weeks. Group III [aluminum chloride treated] received aluminum chloride daily at a dose of 320 mg/kg/l added to the drinking water for 8 weeks. Group IV [aluminum chloride + N. sativa] received N. sativaoil with aluminum for 8 weeks at the same dose as the two previous groups. Group V [withdrawal] received aluminum only without N. sativa oil at the same previous dose for 8 weeks and then the animals were left without treatment for another 4 weeks. Specimens from the hippocampus were processed for light and electron microscopical examination. Also, the immunohistochemical technique was used with glial fibrillary acidic protein [GFAP]. Group III showed apoptotic changes in many pyramidal cells. Moreover, there was a significant decrease in the number of pyramidal cells. These changes were accompanied by a significant increase in GFAP-positive astrocytes. In group IV, minimal apoptotic changes were detected in pyramidal cells, with a significant increase in their number. This was accompanied by a significant decrease in GFAP-positive astrocytes. In group V, many pyramidal cells still showed degenerative changes, with a significant decrease in their number. GFAP-positive cells showed a significant increase. Gliosis was marked in the pyramidal cell layer. One-month withdrawal of aluminum chloride was not sufficient to gain a normal histological appearance of the hippocampus. N. sativa could be used to protect the hippocampus against aluminum chloride-induced damage