Brain Gangliosides in Alzheimer's Disease: Increased Expression of Cholinergic Neuron-Specific Gangliosides.

BACKGROUND Gangliosides are enriched in the neuronal membranes. Gangliosides are shown to interact with amyloid-β proteins, leading to formation of amyloid fibrils in Alzheimer's disease (AD) brains. Several earlier studies indicated that the alterations of ganglioside metabolism could contribute the pathogenesis of AD. METHODS Gangliosides were isolated from the frontal lobes in five patients with AD and three control subjects. Gangliosides were assessed by high performance thin-layer chromatography (HPTLC) with resorcinol staining and immunostaining using mouse monoclonal antibodies against cholinergic neuronspecific (Chol-1α) gangliosides. RESULTS In all AD brains, not only the total sialic acid content but also a-series gangliosides, GM1 and GD1a, were dramatically reduced as compared with those in control subjects. These results are a hallmark of the pathogenesis in AD. In contrast, Chol-1α gangliosides, GT1aα and GQ1bα, which are specific markers of cholinergic neurons, were significantly increased in AD brains. CONCLUSION The expression of Chol-1α gangliosides may be caused by a compensation to preserve the function of the cholinergic neuron and play an important role in cholinergic synaptic transmission.