Effect of neurotransmitters on axoplasmic transport: acetylcholine effect on superior cervical ganglion cells

The effect of acetylcholine (ACh) on particle movements along axons of cultured superior cervical ganglion cells was analyzed with a computer-assisted video-enhanced differential interference contrast microscope system. ACh suppressed the axoplasmic transport reversibly in both anterograde and retrograde directions. A muscarinic agonist, arecoline, mimicked the ACh effect, but nicotine did not. An experiment with the Ca(2+)-indicator dye, fura-2, revealed that ACh suppressed the transport without any change of intracellular Ca2+ concentration. ACh also suppressed the axoplasmic transport in Ca(2+)-free medium. Islet-activating protein (IAP), pertussis toxin, blocked the ACh effect. These results indicate that ACh activates muscarinic receptors and suppresses fast axoplasmic transport through the activation of IAP-sensitive GTP-binding protein, irrespective of Ca2+ ions.