Dentate gyrus changes in an Alzheimer-induced model in adult male albino rats and the possible protection by ginger: Histological and immunohistochemical study

ABSTRACT

Alzheimer's disease [AD] is the most prevalent neurodegenerative disorder, and its incidence is increasing markedly worldwide. It causes progressive cognitive decline and is the most common cause of dementia in the elderly. It has been proven that prolonged aluminum exposure induces Alzheimer-like histopathological changes and hence aluminum was used experimentally to produce an animal model of AD. Ginger has been shown to inhibit and even reverse the deposition of amyloid plaques, which are considered one of the hallmarks of AD. The present study was carried out to determine the histological changes in the dentate gyrus of the hippocampus in an Alzheimer-induced model and investigate the possible ameliorating effect of ginger. Twenty-one adult male albino rats were divided equally into three groups the control group; the Alzheimer-induced model group, which received aluminum chloride [300 mg/kg/day orally] for 1 month; and the ginger-treated group, which received ginger [200 mg/kg/day orally] concomitant with aluminum chloride at the same dose and for the same period as that of the previous group. Temporal lobes of the cerebral cortex were processed with H and E, toluidine blue, silver, and Congo red stains. In addition, inducible nitric oxide synthase expression was assayed by immunohistochemistry. Chronic administration of aluminum chloride induced Alzheimer-like changes in the dentate gyrus, such as distortion of the granular cell layer, increased number of immature neurons, and disturbed arrangement and reduction in the number of pyramidal cells, which appeared with darkly stained pyknotic nuclei. Fine argentophilic neurofibrillary tangles and amyloid plaques were detected, in addition to increased intensity of inducible nitric oxide synthase expression in the granular cell layer. Ginger administration ameliorated the previous histological changes. The findings proved that chronic administration of ginger significantly improved the neurodegenerative changes induced in the Alzheimer model. Hence, it is advisable to drink ginger juice, especially the elderly, who are more susceptible to AD