Transporters and G Protein–Linked Receptors as Targets of Psychopharmacological Drug Action

• Neurotransmitter transporters as targets of drug action
• Classification and structure
• Monoamine transporters (SLC6 gene family) as targets of psychotropic drugs
• Other neurotransmitter transporters (SLC6 and SLC1 gene families) as targets of psychotropic drugs
• Where are the transporters for histamine and neuropeptides?
• Vesicular transporters: subtypes and function
• Vesicular transporters (SLC18 gene family) as targets of psychotropic drugs
• G Protein–linked receptors
• Structure and function
• G Protein–linked receptors as targets of psychotropic drugs
• Summary

Transporters and G Protein–Linked Receptors as Targets of Psychopharmacological Drug Action

Psychotropic drugs have many mechanisms of action, but they all target specific molecular sites having profound effects upon neurotransmission. It is thus necessary to understand the anatomical infrastructure (Chapters 1 and 2) and chemical substrates of neurotransmission (Chapter 3) in order to grasp how psychotropic drugs work (included in this chapter and Chapter 5). Although over 100 essential psychotropic drugs are utilized in clinical practice today (see Stahl SM, Essential Psychopharmacology: The Prescriber’s Guide), there are only a few sites of action for all these therapeutic agents. Specifically, about one-third of psychotropic drugs target one of the transporters for a neurotransmitter (Figure 4-1). Another third target receptors coupled to G proteins (also shown in Figure 4-1). Both of these sites of action are discussed here in Chapter 4.

The molecular sites of action for the other third of psychotropic drugs are discussed in Chapter 5. These include ligand-gated ion channels, voltage-sensitive ion channels, and various enzymes (Figure 4-2). Thus, mastering how just a few molecular sites regulate neurotransmission allows the psychopharmacologist to understand the theories about the mechanisms of action of virtually all psychopharmacological agents.