The proper functioning of our brain requires the right amount of a critical neurotransmitter – glutamate, which is most abundant in our nervous system. It exerts an excitatory effect on neurons, enabling the firing of neurons so that effective communication happens between them. Glutamate influences over 90% of the excitatory function of the human brain.
The concentration of glutamate in the brain is crucial: too little or too much can negatively impact brain functions. Hence, the neurons produce the required amounts and store them in their axon terminals. In addition, to further check the critical concentrations, the blood-brain barrier assists by preventing any glutamate in the blood from entering the brain. Thus, any glutamate available in the diet does not affect the brain.
When a neuron is stimulated, glutamate is released to the outside into the synapse (junction between the neurons) where it binds to the receptors present in nearby neurons. It excites the neurons by binding to the glutamate receptors on their surface, such as NMDA, AMPA, kainite, and G protein-linked receptors. Excessive activation of these receptors is prevented by continuous removal of glutamate from the synapse .
In addition to its excitatory role, glutamate influences learning and memory. Additionally, it can also impact the development of various neurological and psychiatric conditions such as depression, substance use disorder, schizophrenia, epilepsy, neurodegenerative diseases (such as Alzheimer’s disease, amyotrophic lateral sclerosis, multiple sclerosis, Huntington’s chorea) and mood issues.
Excessive release of glutamate can cause over-excitation of neurons leading to excitotoxicity and neurodegeneration, says Dr A Nalini, professor, department of neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru. “The glutamate excitotoxicity is one of the major factors in the neurodegeneration observed in amyotrophic lateral sclerosis”, she adds. At the same time, inadequate levels of glutamate can lead to difficulties in concentration, mental exhaustion, insomnia and low energy.
Due to its involvement in various neurological conditions, it is a choice target for designing targeted drugs for neurological conditions.
The following infographic describes the role of glutamate in the central nervous system.
Read more: When muscle falters: Exploring amyotrophic lateral sclerosis
Read more: Voices and visions of schizophrenia
Read more: Synapse: how neurons communicate
