Glutamic acid, also called glutamate, is an essential amino acid your body uses to make proteins. But it also acts as an excitatory neurotransmitter in your central nervous system, which includes both your brain and spinal cord. Glutamic acid is the most common neurotransmitter in your brain and spinal cord. As a neurotransmitter, glutamic acid influences other neurotransmitters and plays roles in several neuropsychological conditions. Several foods that you eat contain glutamic acid.
Function
Glutamic acid acts as an excitatory neurotransmitter, meaning it increases activity in the central nervous system. About 25 percent of all glutamic acid acts as a neurotransmitter, according to Randolph B. Schiffer, Stephen M. Rao and Barry S. Fogel, authors of "Neuropsychiatry." Glutamic acid affects several areas of your brain, including the spinal cord, thalamus, brain stem, basal ganglia and pons. To act as a neurotransmitter, glutamic acid must attach itself to specific receptors in the central nervous system. One such receptor is the N-methyl-D-aspartate receptor, also called the NMDA receptor. This type of glutamic acid receptor regulates the number of magnesium, calcium and sodium ions that enter and leave the cells.
Effects
In addition to being a neurotransmitter itself, glutamic acid also helps form another neurotransmitter, gamma-aminobutyric acid, also called GABA. The enzyme glutamic acid decarboxylase converts glutamate into GABA. An inhibitory neurotransmitter, GABA reduces activity in the central nervous system. Lower levels of GABA can result in anxiety or epilepsy.
Neuropsychological Conditions
Glutamic acid as a neurotransmitter plays a role in several neuropsychological and neurological conditions. The neurotransmitter can become toxic to neurons if too much of the neurotransmitter is present. For example, excessive glutamic acid results in the neurological condition amyotrophic lateral sclerosis, in which the neurons involved in voluntary muscle control become damaged. Glutamic acid can also contribute to memory problems and obsessive-compulsive disorder. Interruption of glutamic acid can interfere in the formation of memories, and the Alzheimer's disease medication memantine affects glutamic acid and helps improve cognitive abilities in patients. Glutamic acid, along with other neurotransmitters such as dopamine, serotonin and GABA, may affect the development of obsessive-compulsive disorder, a type of anxiety disorder. It may also play a role in addictive behavior.
Food Sources
Foods that are high in protein, such as fish, eggs, dairy, meat and poultry, contain glutamic acid. Plants can also contain glutamic acid. The discoverer of glutamic acid, Kikunae Ikeda, extracted the acid from seaweed.
References
- Shippensburg University: Neurotransmitters
- University of Michigan Health System: Glutamic Acid
- "Neuropsychiatry"; Randolph B. Schiffer, Stephen M. Rao and Barry S. Fogel; 2003
- "The Brain and Behavior: An Introduction to Behavioral Neuroanatomy"; David Lee Clark, Nashaat N. Boutros and Mario F. Mendez; 2005
- "Abnormal Psychology"; Ronald J. Comer; 2009
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