How is serotonin released?

Your own cells: There are some precursors like L Tryptophane but your own neurons will synthesize it in very selective areas where this neurotransmission takes place. FkFl

Complex: It is a neurotransmitter, mostly in the brain and the gi system. It is released when that neuron electrically achieves an action potential, based on its interactions with other neurons. Those interactions are complex. What is more complex is the many different kinds of receptors, which do many different things.