Excitatory amino acids refer to a group of amino acids that act as neurotransmitters in the central nervous system (CNS) and have the ability to stimulate the activity of neurons. These amino acids include glutamate and aspartate, which are the most prevalent ones in the brain.
Excitatory amino acids play a crucial role in various CNS functions, such as synaptic transmission, learning, memory, and neuronal development. They bind to specific receptors on the postsynaptic membranes of neurons, leading to excitatory postsynaptic potentials (EPSPs) and the generation of nerve impulses.
Glutamate, the most abundant excitatory amino acid in the brain, acts through various receptor types, including NMDA (N-methyl-D-aspartate), AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid), and kainate receptors. These receptors are involved in mediating different aspects of neuronal communication, synaptic plasticity, and long-term potentiation (a molecular mechanism underlying learning and memory formation).
While excitatory amino acids are critically important for proper brain function, excessive or prolonged activation of their receptors can be harmful. Overstimulation of the receptors leads to an influx of calcium ions, which can trigger a cascade of detrimental events, including excitotoxicity, oxidative stress, and neuronal cell death. Excitotoxicity is strongly associated with various neurodegenerative disorders and acute brain injuries, such as stroke.
Understanding the role of excitatory amino acids and the regulation of their receptors is crucial in both physiological and pathological contexts, as it provides insights into the complex mechanisms that underlie brain function and dysfunction.
