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".
Tuberomammillary nucleus
The tuberomammillary nucleus is the sole source of histamine pathways in the human brain. The densest axonal projections from the tuberomammillary nucleus are sent to the cerebral cortex, hippocampus, neostriatum, nucleus accumbens, amygdala, and other parts of the hypothalamus. The projections to the cerebral cortex directly increase cortical activation and arousal, and projections to acetylcholinergic neurons of the basal forebrain and dorsal pons do so indirectly, by increasing the release of acetylcholine in the cerebral cortex.