Effects of Melatonin on Lipid Membrane Induced Aggregation of Amyloid Beta

Abstract

Alzheimer's disease is a progressive neurodegenerative disease associated with amyloid fibril formation in the brain. The exact molecular mechanism of amyloid fibril formation and toxicity is not well understood, which delays development of novel and effective approaches to prevent and treat the disease. Some studies show that hormone “melatonin”, which regulates and maintains the body's circadian rhythm, may counteract the effects of amyloid toxicity, most likely as a radical scavenger. In addition, melatonin may have effects on the membrane surface perturbation by amyloid-beta in its initial stages of aggregation. Thus, we investigated the molecular interaction between early stage amyloid-beta aggregates on the lipid membrane, and the effects of melatonin in ensemble. We used Atomic Force Microscopy (AFM) imaging and AFM-based force spectroscopy in discovering melatonin's affects on the aggregation of amyloid-beta on the lipid bilayer membrane surface. The results show that melatonin may decreased the aggregate formation on the lipid membrane surface and also alter the positioning of amyloid-beta aggregates within the lipid bilayer. We suggest that melatonin changes in the interaction between small aggregates of amyloid-beta and the lipid bilayer, and this effect may be an important aspect in its protective effects.