Optical measurements of presynaptic nicotinic effects

We have used me styryl dye FM 2-10 to monitor changes in synaptic activity mediated by nicotinic acetylcholine receptors (AChRs) on cultured hippocamp al neurons. We show that both 100 muM ACh and nicotine at 20 muM causes a s ignificant increase in staining intensities of presynaptic boutons in the p resence of 0.5 muM tetrodotoxin (TTX). This effect of nicotine is blocked b y d-tubocurarine. Interestingly, nicotine also had a long-lasting effect on high potassium-induced staining of boutons. These results suggest that nic otine can have significant and sustained effects on synaptic efficacy in cu ltured hippocampal neurons. (C) 2000 Elsevier Science Ltd. All rights reser ved.