Glutamate

Glutamate is the most abundant excitatory neurotransmitter in the brain. In balance with GABA it is essential for learning, memory and synaptic plasticity. If glutamate acts too strongly or for too long in the brain, it can overstimulate and damage nerve cells (excitotoxicity); inflammation and an imbalance with GABA are considered in this context, and magnesium slows the NMDA receptor. Measured in Neurotransmitter Plus.

What glutamate does in the body

Glutamate is made from glutamine and from alpha-ketoglutarate, an intermediate of energy metabolism to which other amino acids transfer their amino group (vitamin B6 is needed for this). In the brain, nerve cells store glutamate in vesicles and release it at the contact points. It binds to AMPA and NMDA receptors on the next cell; sodium and calcium flow in and the signal is passed on. At rest the NMDA receptor is blocked by magnesium and only opens with strong excitation – the calcium pulse that then flows in strengthens connections between nerve cells and is one basis of learning and memory. Support cells rapidly take glutamate back up, convert it into glutamine and return it to the nerve cells. From glutamate, glutamate decarboxylase with vitamin B6 forms the inhibitory messenger GABA. Outside the brain, glutamate is a hub of nitrogen metabolism and a building block of glutathione. Glutamate from the blood hardly crosses the blood-brain barrier; values in blood or urine therefore mainly reflect metabolism in the rest of the body.

Low glutamate – what does it mean?

Low values in blood or urine show that less glutamate is coming from protein and metabolism or that it is being processed further to a greater extent – for example into glutamine to bind ammonia, or into glutathione when antioxidant demand is high. No consequence for the brain can be derived from this, because the brain makes its own glutamate. When little glutamate is available to the body overall, starting material for glutathione and GABA is lacking.

High glutamate – what happens in the body?

If glutamate stays at the contact points in the brain for too long, NMDA receptors remain open: so much calcium flows into the nerve cells that enzymes become overactive, the mitochondria come under pressure and cells can be damaged – this is called excitotoxicity. Reuptake by the support cells needs energy; it stalls with lack of oxygen and energy and is slowed by inflammatory messengers, and activated immune cells of the brain release glutamate themselves. In the nervous system, excitation then outweighs inhibition by GABA. Elsewhere in the body, raised glutamate values in the blood have been observed in studies with insulin resistance and excess weight.

The interpretation is given in your report.