Substrate-bound laminin pathways prepared by the method of Hammarback et al. [J. A. Hammarback, S. L. Palm, L. T. Furcht, and P. C. Letourneau 1985. J. Neurosci. Res.13, 213-220] guided peripheral nervous system neurites (dissociated dorsal root ganglia and sympathetic ganglia) and central nervous system neurites (dissociated spinal cord and brain). Guidance of individual growth cones by 7- to 10-μm-wide laminin pathways was observed using time-lapse video microscopy. Fibronectin pathways, produced by the method used for laminin pathways, did not guide neurites. The guidance effect of laminin pathways was quantified and found to correlate with the concentration of laminin initially applied to the substratum. The concentration of laminin initially applied to the substratum also correlated with increased adhesivity of dorsal root ganglia (DRG) neurons to laminin constituting the pathways relative to uv-irradiated laminin that borders the pathways. The guidance effect of laminin pathways was blocked by anti-laminin antibodies or by laminin but not by anti-fibronectin antibodies. This study demonstrates that guidance of DRG neurites by laminin occurs at the growth cone in a manner consistent with the hypothesis of guidance by differential neuron-to-substratum adhesivity.
Bibliographical noteFunding Information:
This work was supported by grants from the National Institutes of Health (HD 19950 and HD 1’7192), the Spinal Cord Society, and a Minnesota Medical Foundation, the Muscular Dystrophy Association, and a National Science Foundation to P.C.L., and a grant from the Leukemia Task Force and Grants CA29995 and CA21436 from the National Institutes of Health to L.T.F.