Vascular endothelial growth factor is a neurotrophic factor which stimulates axonal outgrowth through the flk-1 receptor.
Vascular endothelial growth factor (VEGF) is an angiogenic factor that stimulates axonal outgrowth. Here we used in situ hybridization and immunocytochemistry to study the VEGF receptor flk-1 in cultured superior cervical ganglia (SCG) and dorsal root ganglia (DRG) from adult mice, and also the effects of VEGF on regeneration in vitro. Neurons in both ganglia contained the flk-1 receptor and showed an increased mRNA expression and immunoreactivity for flk-1 after 48 h in culture. In SCG, but not in DRG, double immunostaining for flk-1 and VEGF revealed coexpression in many neurons, implying that VEGF may exert both autocrine and paracrine actions. One proportion of the flk-1-positive neurons in DRG stained positive for the large neuron marker RT97 and another proportion expressed calcitonin gene-related peptide (CGRP). Small IB4-positive neurons were devoid of flk-1 immunoreactivity. Most flk-1-positive neurons in the DRG, but not in the SCG, were also immunoreactive to neuropilin-1. VEGF was found to stimulate axonal outgrowth from DRG, both by an action on the growing axons and the nerve cell bodies. The latter effect could be mediated by retrograde axonal transport as revealed by the use of a two compartment system to assay axonal outgrowth. We also found that the VEGF-induced axonal outgrowth was blocked by the flk-1 inhibitor SU5416. The results strongly suggest that VEGF acts as a neurotrophic factor and plays an important role during the regeneration of peripheral nerves.
Sondell
M
M
Department of Animal Physiology, Lund University, Helgonav. 3 B, S-223 62, Lund, Sweden. Mariann.Sondell@zoofys.lu.se
Sundler
F
F
Kanje
M
M
D000818:Animals; D001370:Axonal Transport / Q000187:drug effects; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D015740:Calcitonin Gene-Related Peptide / Q000235:genetics; D016228:Endothelial Growth Factors / Q000494:pharmacology*; D007839:Functional Laterality; D005727:Ganglia, Spinal / Q000187:drug effects / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008222:Lymphokines / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009409:Nerve Crush; D020932:Nerve Growth Factor / Q000494:pharmacology; D009416:Nerve Regeneration / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009924:Organ Culture Techniques; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000502:physiology; D017978:Receptors, Growth Factor / Q000235:genetics* / Q000502:physiology; D011975:Receptors, Mitogen / Q000502:physiology; D040262:Receptors, Vascular Endothelial Growth Factor; D011994:Recombinant Proteins / Q000494:pharmacology; D012584:Sciatic Nerve / Q000187:drug effects / Q000502:physiology; D017783:Superior Cervical Ganglion / Q000187:drug effects / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D017978:Receptors, Growth Factor; D011975:Receptors, Mitogen; D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D020932:Nerve Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D015740:Calcitonin Gene-Related Peptide