LOCUS-COERULEUS NEURON GROWTH CONES AND SPINAL-CORD REGENERATION

One of the major impediments to successful recovery of function after a spinal cord injury is thought to be the reaction of the neuronal gro wth cone to inhibitory influences in the local environment in or aroun d the site of the injury. The growth cones of locus coeruleus neurons studied in vitro collapsed upon contact with an extract of CNS myelin but did not collapse on contact with an extract of PNS myelin. Coincid ent with the collapse of the growth cone, was an increase in internal free calcium concentration that was predominantly the result of an inf lux of calcium through channels in the plasma membrane. Omega-conotoxi n, which specifically blocks N-type voltage-gated calcium channels, bl ocked both the myelin-induced calcium influx and the coincident collap se of the growth cone.