Table 1.
Main serotonin (5-hydroxytryptamine or 5-HT) receptor subtypes in the gut
| 5-HT1A | 5-HT1B/D | 5-HT2A | 5-HT2B | 5-HT3 | 5-HT4 | 5-HT7 | 5-HT1P* | |
| Agonists | 8-OH-DPAT | Sumatriptan | α-Me-5-HT | α-Me-5-HT | 2-Me-5-HT | Tegaserod | 5-CT 8-OH | Hydroxylated indalpines |
| Buspirone | Rizatriptan | BW723C86 | CPBG | Prucalopride | DPAT | |||
| Naratriptan | ||||||||
| Antagonists | WAY100635 | GR127935 (5-HT1B/D antagonist) | Ketanserin, | SB200646 | Ondansetron | GR113808 | Methiotepin | 5-HTP-DP |
| SB216641 (5-HT1B-selective) | MDL100907 | SB204741 | Alosetron | GR125487 | Metergoline | |||
| BRL15572 (5-HT1D–selective) | Cilansetron | Piboserod | SB258719 | |||||
| SB269970 | ||||||||
| SB656104 | ||||||||
| Effectors | Gi/o | Gi/o | Gq/11 | Gq/11 | Ligand gated ion channel | Gs | Gs | Go |
| Distribution in the gut | Enteric neurones | Enteric neurones (?) | Smooth muscle | Longitudinal smooth muscle | Enteric neurones | Enteric neurones, smooth muscle, enterocytes | Smooth muscle, enteric neurones (?) | Enteric neurones |
| Circular smooth muscle (?) | ||||||||
| Functional response on stimulation | ↓Transmitter release | Gastric relaxation | Contraction | Contraction | fEPSP, ↑ transmitter release, ↑secretion | ↑Transmitter release, relaxation, ↑ secretion | Relaxation | Slow EPSP |
8-OH-DPAT, 8-hydroxy-2-(di-n-propylaminotetralin); 5-CT, 5-carboxamidotryptamine; CPBG, chlorophenyl-biguanide; 5-HTP-DP, N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophanamide (a dipeptide); fEPSP, fast excitatory postsynaptic potential.
*5-HT1P receptors are not included in the IUPHAR nomenclature of 5-HT receptors and are still considered an “orphan” receptor subtype.