Bioactive Peptides in Neurodegenerative Diseases

Bioactive peptides, isolated small fragments of proteins, are involved in several biological activities and significantly contribute to human physiological responses. This chapter offers a brief introduction to bioactive peptide application in neurodegenerative diseases (NDDs). Major NDDs include Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease, amyotrophic lateral sclerosis, frontotemporal dementia, and spinocerebellar ataxias. Reactive oxygen species (ROS) are highly reactive chemical molecules formed by the partial reduction of oxygen. Glutamate excitotoxicity is another mechanism of neuronal cell death induced by oxidative stress in neurodegenerative disease, such as AD and PD. Accumulation of glutamate and unnecessary stimulation of its receptors leads to cell death through different mechanisms including ROS generation, mitochondrial dysfunction, and overload of calcium. The imbalance between ROS amount and antioxidant systems leads to apoptosis and also affects gut microbiota, which have been shown to be associated with neurodegenerative disease.