Brain
There are dozens of other chemical neurotransmitters that are used in more limited areas of the brain, often areas dedicated to a particular function. Serotonin, for example—the primary target of antidepressant drugs and many dietary aids—comes exclusively from a small brainstem area called the raphe nuclei. Norepinephrine, which is involved in arousal, comes exclusively from a nearby small area called the locus coeruleus. Other neurotransmitters such as acetylcholine and dopamine have multiple sources in the brain, but are not as ubiquitously distributed as glutamate and GABA.
Neurotransmission
Some neurons can release at least two neurotransmitters at the same time, the other being a cotransmitter, in order to provide the stabilizing negative feedback required for meaningful encoding, in the absence of inhibitory interneurons. Examples include:
Noradrenaline and ATP are sympathetic co-transmitters. It is found that the endocannabinoid anadamide and the cannabinoid, WIN 55,212-,2 can modify the overall response to sympathetic nerve stimulation, and indicate that prejunctional CB1 receptors mediate the sympatho-inhibitory action. Thus can cannabinoids inhibit both the noradrenergic and purinergic components of sympathetic neurotransmission.