The possible protective effect of Gardenia Jasminoides extracts on the dentate gyrus changes in an Alzheimer-induced model in adult male albino rats: Histological and Immunohistochemical study

Introduction: Alzheimer's disease (AD) is the most common diagnosed form of senile dementias, a neurodegenerative disease resulting in cognitive impairment in the elderly. Geniposide, extracted of Gardenia Jasminoides, is widely used herb for brain diseases and reduce amyloid plaques deposition which is an intricate process in AD.
Aim of the work: demonstrate the histological changes in the dentate gyrus of hippocampus in an Alzheimer-induced model and the possible neuroprotective effect of Gardenia Jasminoides extract.
Materials and methods: Thirty six adult male albino rats(4-6 months) , weighing180-200g divided into 3 groups. Group I the control group, group II given aluminum chloride dissolved in distilled water, (300mg/kg/day) orally for one month. Group (III) given Geniposide in distilled water,at a dose of (100mg/kg/day) orally concomitant with aluminum chloride at the same dose and period of the previous group. Cognitive functions were assessed by the passive avoidance test. Temporal lobes processed for H&E , congo red stains. Immunohistochemical study for detection of (GFAP) and (INOS). Tau protein can be phosphorylated by glycogen synthase Kinase-3β(GSK-3 β). Western blot assay to investigate the total protein expression glycogen synthase Kinase-3β(GSK-3 β) . Comet assay to detect DNA damage.
Results: Alzheimer-induced model group showed significantly impaired cognitive performance which was improved after treatment with Geniposide extract. Changes in the dentate gyrus apparent increase in immature neurons, disturbed granular cell layer, distortion of pyramidal cells that appeared with pyknotic nuclei. Positive immunoreaction for GFAP in astrocytes were also observed. The ultra structural study exhibited neurons with apoptotic features, heterochromatic nuclei and their cytoplasm contained dilated cisternae of rough endoplasmic reticulum. Gardenia extracts ameliorated histological alterations.
Conclusion: Gardenia Jasminoides extracts significantly ameliorated the neuro- degenerative alterations induced in the Alzheimer model. Daily supplements of Gardenia Jasminoides extracts might be of benefit for the elderly people at risk of developing AD.