Glycine receptor and 5-HT3 receptor (GlyR / 5-HT3R)

The Glycine receptor (GlyR) and the 5-HT3 receptor (5-HT3R) are distinct members of the Cys-loop superfamily of pentameric ligand-gated ion channels (pLGICs) (Thompson & Lummis, 2007). Although they share a common structural architecture—comprising five subunits arranged around a central ion-conducting pore—they mediate fundamentally different physiological processes. GlyRs are primarily inhibitory chloride channels located in the spinal cord and brainstem, where they regulate motor rhythm and sensory processing; mutations in GlyR subunits are linked to hyperekplexia, also known as startle disease (Lynch, 2004). In contrast, 5-HT3Rs are excitatory cation channels (permeable to Na+, K+, and Ca2+) widely expressed in the peripheral and central nervous systems, playing a pivotal role in the emetic reflex and gastrointestinal motility (Walstab et al., 2010). Pharmacologically, 5-HT3R antagonists, such as ondansetron, are gold-standard treatments for chemotherapy-induced nausea and vomiting, while GlyRs are investigated as targets for novel analgesics and muscle relaxants (Breitinger, 2013). Both receptors are sensitive to modulation by general anesthetics, alcohols, and certain neurosteroids, which often act as allosteric modulators to alter channel gating and synaptic strength (Mashimo et al., 2001).

Other names

Glycine-gated chloride channel5-hydroxytryptamine receptor 3Serotonin-gated ion channelCys-loop ligand-gated ion channelsGlyR5-HT3R

Antagonism of 5-HT3 receptors to inhibit excitatory signaling in the emetic reflex and gut; Agonism or positive allosteric modulation of Glycine receptors to enhance inhibitory signaling in the spinal cord; Allosteric modulation by general anesthetics and alcohols.