1. Effects of 5-hydroxytryptamine (5-HT) on neuronal nicotinic acetylcholine (ACh) receptor channels were investigated by expressing cloned channel subunits in Xenopus oocytes. 2. When channels were expressed with a combination of α3 and β4 subunits, 5-HT (10 to 300 μM) reversibly inhibited an inward current activated by 100 μM ACh in a concentration-dependent manner. The inhibition was also observed when α3 subunit was combined with β2 subunit instead of β4 subunit, or β4 subunit was combined with α2 or α4-1 subunit instead of α3 subunit to express channels. 3. Compounds known to antagonize at 5-HT receptors (LY53857, metoclopramide and propranolol) exhibited an agonistic effect: they inhibited the ACh-activated current. 4. The results suggest that 5-HT inhibits recombinant neuronal nicotinic receptor channels through a binding-site distinct from conventional 5-HT receptors. The binding-site may not be attributed to a unique type of channel subunits.
All Science Journal Classification (ASJC) codes
- Cellular and Molecular Neuroscience
- Cell Biology