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".
5-HT1A receptor
The 5-HT receptor is the most widespread of all the 5-HT receptors. In the central nervous system, 5-HT receptors exist in the cerebral cortex, hippocampus, septum, amygdala, and raphe nucleus in high densities, while low amounts also exist in the basal ganglia and thalamus. The 5-HT receptors in the raphe nucleus are largely somatodendritic autoreceptors, whereas those in other areas such as the hippocampus are postsynaptic receptors.