Glutamic acid
Glutamate is also a neurotransmitter (see below), which makes it one of the most abundant molecules in the brain. Malignant brain tumors known as glioma or glioblastoma exploit this phenomenon by using glutamate as an energy source, especially when these tumors become more dependent on glutamate due to mutations in the gene "IDH1".
Spinal interneuron
The sensory information that is transmitted to the spinal cord is modulated by a complex network of excitatory and ihibitory interneurons. Different neurotransmitters are released from different interneurons, but the two most common neurotransmitters are GABA, the primary inhibitory neurotransmitter and glutamate, the primary excitatory neurotransmitter. Acetylcholine is a neurotransmitter that often activates interneurons by binding to a receptor on the membrane.