The dentate gyrus neurogenesis: a therapeutic target for Alzheimer's disease

Neurogenesis persists in the aged human dentate gyrus but its role and regulation in pathological conditions such as Alzheimer's disease (AD), where the neurotrophic environment is changed, are poorly understood. In this study we investigated the effect of changes in the neurotrophic environment on neurogenesis in cultured rat hippocampal progenitors and in normal adult rats as models. In hippocampal progenitor cells from adult rats, fibroblast growth factor-2 (FGF-2) dose-dependently decreased microtubule-associated protein 2 and increased tau levels, indicating an FGF-2-induced dendrite to axon polarity shift. Cerebrolysin, a neurotrophic drug which has been shown to improve cognition and mood of AD patients, was found to increase neuron-like differentiated adult rat hippocampal progenitors in culture both by reducing apoptosis and by counteracting the FGF-2-induced polarity shift. Intraperitoneal administration of Cerebrolysin enhanced dentate gyrus neurogenesis and maze performance of 8- to 12-month-old female rats. These studies suggest that AD pathogenesis might involve an abnormally elevated FGF-2-associated dysregulation of dentate gyrus neurogenesis, especially neuronal polarity and that the neurogenesis pathology is a promising therapeutic target for this disease.