Neurotransmitters

Glutamate is the major excitatory neurotransmitter in the brain.

GABA and glycine are the major inhibitory transmitters in the brain.

For the moment, just consider the amino acids in the image below. Glutamate and aspartate are very similar, glycine too. If aspartate or glutamate levels are too high, then some neurons will be excited to death in a process known as "excitotoxicity".

Glutamate is an agonist for NMDA receptors.

Health note: aspartame is the chemical name for the brand names of artificial sweetners such as NutraSweet, Equal, Spoonful, and Equal-Measure. Aspartame is 40% aspartic acid and 50% phenylalanine. It accounts for over 75 percent of the adverse reactions to food additives reported to the FDA in the US. Are you excited?

Image: Purves et al, 2001.