Home > Conscious > Chapter 6 > 6.3. The GPCRs Coupled with GIRK Channels

 

As described in Chapter 3, neurotransmitter receptors can be divided into two categories: one belonging to ligand-gated ion channels, and the other the members of G protein-coupled receptors (GPCRs). Each ligand-gated ion channel can be activated by only one type of neurotransmitters. For instance, the GABAA receptor can be activated only by GABA, while the NMDA receptor can be activated only by glutamate, although they could be activated by other agonists which, however, are not endogenous neurotransmitters. In contrast, a variety of neurotransmitters can act on their specific GPCRs, promoting the dissociation of Gβγ from Gα, thereby opening GIRK channels (Figure 6-4). The major GPCRs coupled with GIRK channels are listed below, together with their impact on the conscious system.

  • Adenosine's A1 receptor increases sleep pressure (Chapter 7).
  • Melatonin's MT1 or MT2 receptor facilitates sleep (Chapter 7).
  • GABA's GABAB receptor is involved in mental disorders (Chapter 14).
  • Dopamine's D2 receptor plays important roles in action selection (Chapter 13).
  • Serotonin's 5-HT1A receptor affects mood (Chapter 14).
  • Opioid's (e.g., morphine and heroin) μ, δ or κ receptors have analgesic effects (Chapter 12), but also addictive (Chapter 13).
Images

Figure 6-4. The GPCRs coupled with GIRK channels. Activation of GPCR can lead to the opening of GIRK channels by Gβγ. This figure shows only the adenosine's A1 receptor, melatonin's MT1 or MT2 receptor, and GABA's GABAB receptor. [Adapted from Sohn, 2013]