Neurotransmitters

1. Monoamines
   • ; they contain one amine group. Monoamines include dopamine, norepinephrine, epinephrine, and serotonin.
     1. Catecholaminergic pathways
        • make use of a monoamine that contains a catechol nucleus. Catecholamines include dopamine, norepinephrine, and epinephrine.
        • include dopaminergic, noradrenergic (norepinephrinergic), and adrenergic (epinephrinergic) pathways.
     2. Indolaminergic pathways
        • make use of a monoamine that contains an indole nucleus. Serotonin is an indolamine.
        • include serotonergic pathways.
2. Cholinergic pathways
   • make use of acetylcholine (ACh) as a neurotransmitter.
3. Peptidergic pathways
   • make use of peptides as neurotransmitters.
4. Gamma-aminobutyric acid (GABA)–ergic pathways
   • make use of GABA as a neurotransmitter.
5. Glutamatergic pathways
   • make use of glutamate as a neurotransmitter.
6. Glycinergic pathways
   • make use of glycine as a neurotransmitter.
7. L-Arginine–nitric oxide pathway
   • makes use of the gaseous neurotransmitter nitric oxide. (Figure 21.1)