Summary
1. Effects of 5-hydroxytryptamine (5-HT) on neuronal nicotinic acetylcholine (ACh) receptor channels were investigated by expressing cloned channel subunits inXenopus oocytes.
2. When channels were expressed with a combination ofα 3 andβ 4 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 whenα 3 subunit was combined withβ 2 subunit instead ofβ 4 subunit, orβ 4 subunit was combined withα 2 orα 4−1 subunit instead ofα 3 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.
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Nakazawa, K., Akiyama, T. & Inoue, K. Block by 5-hydroxytryptamine of neuronal acetylcholine receptor channels expressed inXenopus oocytes. Cell Mol Neurobiol 15, 495–500 (1995). https://doi.org/10.1007/BF02071882
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DOI: https://doi.org/10.1007/BF02071882