Final answer:
The major neurotransmitters relevant in psychiatry include dopamine, serotonin, norepinephrine, glycine, glutamate, aspartate, GABA, substance P, and endorphins.
Step-by-step explanation:
The known major neurotransmitters that are relevant in psychiatry include dopamine, serotonin, norepinephrine, glycine, glutamate, aspartate, gamma aminobutyric acid (GABA), substance P, and endorphins. These neurotransmitters play important roles in the communication between neurons and are involved in various psychiatric disorders. For example, imbalances in dopamine and serotonin have been linked to depression, while imbalances in norepinephrine and GABA have been associated with anxiety disorders.