Growth cones exhibit enhanced cell-cell adhesion after neurotransmitter release

Evoked release of acetylcholine and subsequent cell-cell adhesive contacts between growth cones and acetylcholine sensing neurons were observed using cultured neurons dissociated from the diagonal band of Broca of the rat. St imulation to the soma of the diagonal band of Broca neurons evoked release of acetylcholine from the growth cones. The release of acetylcholine was mo nitored using whole-cell patch-clamp recording from acetylcholine receptor- rich superior cervical ganglion neuron positioned on the growth cone as a s ensor of acetylcholine release. By measuring changes in fluorescence from t he growth cone using Ca2+-sensitive dye while voltage-clamping the superior cervical ganglion neuron, transient intracellular Ca2+ concentration incre ase and acetylcholine release from growth cone were recorded simultaneously . Video-enhanced differential interference contrast imaging of the growth c ones demonstrated tether formation between the growth cone and superior cer vical ganglion cell soma when the superior cervical ganglion cell soma was moved away from the growth cone after acetylcholine release, suggesting for mation of adhesive contacts between the growth cone and the sensor neuron. Adhesive contacts between growth cones and sensor neurons were also detecte d when a high K+ solution or alpha-latrotoxin was applied to the growth con e. Adhesions were also observed between growth cones and latex beads, when growth cones were exposed to high K+ solution. The properties of the adhesi ve contacts at the growth cone were studied by optically manipulating a lat ex bead attached to the growth cone surface. These results suggest that gro wth cones exhibit cell-cell adhesion after neurotransmitter release. (C) 19 99 IBRO. Published by Elsevier Science Ltd.