Glutamate is the major excitatory neurotransmitter in the nervous system. They are strategically situated on several cell types converging on the glutamate synapse: pre- and post-synaptic neurons, astrocytes (a type of glial cell), and nearby inhibitory neurons that use γ-Aminobutyric acid (GABA).

What happens when you have too little glutamate?

“Glutamate is a pivotal transmitter in the brain, the crucial link in circuits involved in memory, learning and perception. Too much glutamate leads to seizures and the death of brain cells. Too little glutamate can cause psychosis, coma and death.

Glutamate (the conjugate base of glutamic acid) is abundant in the human body, but particularly in the nervous system and especially prominent in the human brain where it is the body's most prominent neurotransmitter, the brain's main excitatory neurotransmitter, and also the precursor for GABA, the brain's main .

Glutamate is the most abundant free amino acid in the brain and is at the crossroad between multiple metabolic pathways. Considering this, it was a surprise to discover that glutamate has excitatory effects on nerve cells, and that it can excite cells to their death in a process now referred to as “excitotoxicity”. This effect is due to glutamate receptors present on the surface of brain cells. Powerful uptake systems (glutamate transporters) prevent excessive activation of these receptors by continuously removing glutamate from the extracellular fluid in the brain. Further, the blood–brain barrier shields the brain from glutamate in the blood. The highest concentrations of glutamate are found in synaptic vesicles in nerve terminals from where it can be released by exocytosis. In fact, glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. It took, however, a long time to realize that. The present review provides a brief historical description, gives a short overview of glutamate as a transmitter in the healthy brain, and comments on the so-called glutamate–glutamine cycle. The glutamate transporters responsible for the glutamate removal are described in some detail.

Drugs which decrease glutamate?

Glutamatergic Drugs

Riluzole is a glutamate modulator used in the treatment of amyotrophic lateral sclerosis.

 Memantine is an NMDA antagonist used in the treatment of Alzheimer's disease.

Anticonvulsant, Ketamine, Glycine, Sarcosine.

The sympathomimetic psychomotor stimulants, including cocaine, amphetamines, and the phenylethylamine amphetamine-like derivatives, exert actions in mammalian systems that implicate involvement of the excitatory neurotransmitter, glutamate and its receptors.

Seven Major Neurotransmitters

Acetylcholine. A neurotransmitter used by neurons in the PNS and CNS in the control of functions ranging from muscle contraction and heart rate to digestion and memory.

Norepinephrine

Serotonin

Dopamine

GABA

Glutamate

 Endorphin.

Neurotransmitters

Neurotransmitters are endogenous chemicals that enable neurotransmission. It is a type of chemical messenger which transmits signals across a chemical synapse, such as a neuromuscular junction, from one neuron (nerve cell) to another "target" neuron, muscle cell, or gland cell.

Excitatory neuro transmitters

Acetylcholine (ACh) is an excitatory, small-molecule neurotransmitter involved in synaptic transmission at neuromuscular junctions controlling the vagus nerve and cardiac muscle fibers, as well as in the skeletal and visceral motor systems and various sites within the central nervous system.