Tetrodotoxin-sensitivity of nicotine-evoked dopamine release from rat striatum.
Recent observations from synaptosome preparations have questioned the tetrodotoxin (TTX) insensitivity of nicotine-evoked release in the striatum, a characteristic previously considered diagnostic of presynaptically located nicotinic acetylcholine receptors (nAChRs). Therefore, we have undertaken a comparison of nicotine-evoked dopamine release in the presence of TTX from the rat striatum in vitro, using synaptosomes and brain slices, and in vivo, using microdialysis. In P2 and Percoll-purified synaptosome preparations, 1.5 microM TTX partially inhibited nicotine-evoked [3H]dopamine release by 54% and 37%, respectively, whereas in more intact preparations (brain slices and microdialysis) TTX completely inhibited mecamylamine-sensitive nicotine-stimulated dopamine release. These results suggest that caution should be exercised in the interpretation of TTX sensitivity of nicotine-evoked responses with regard to the location of nAChRs.
Marshall
D
D
School of Pharmacy and Pharmacology, University of Bath, U.K.
Soliakov
L
L
Redfern
P
P
Wonnacott
S
S
D000818:Animals; D018678:Cholinergic Agents / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism*; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D017551:Microdialysis; D017072:Neostriatum / Q000187:drug effects / Q000378:metabolism*; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology*
D018678:Cholinergic Agents; D018722:Nicotinic Agonists; D013779:Tetrodotoxin; D008464:Mecamylamine; D009538:Nicotine; D004298:Dopamine