BDNF and NGF signals originating from sensory ganglia promote cranial motor axon growth
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After exiting the hindbrain, branchial motor axons reach their targets in association with sensory ganglia. The trigeminal ganglion has been shown to promote motor axon growth from rhombomeres 2/3 and 4/5, but it is unknown whether this effect is ganglion specific and through which signals it is mediated. Here, we addressed these questions by co-cultures of ventral rhombomere 8 explants with cranial and spinal sensory ganglia in a collagen gel matrix. Our results show that all cranial sensory ganglia and even a trunk dorsal root ganglion can promote motor axon growth and that ganglia isolated from older embryos had a stronger effect on the axonal growth than younger ones. We found that brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are necessary and sufficient for this effect. Altogether, our results demonstrate that the promoting effect of sensory ganglia on cranial motor axon growth is stage dependent, but not ganglion specific and is mediated by BDNF and NGF signals.
KeywordsSensory ganglion Cranial motor neuron BDNF NGF Axonal growth
We are grateful for the technical assistance of Sandra Graefe in the Institute of Anatomy and Mr. Heinz Bioernsen in the Institute of Animal Science. We thank Developmental Studies Hybridoma Bank, Iowa City, IA, USA, for the antibody. This work was supported by grant of the DFG-Hu 729/10 and DFG-Hu 729/13 to R.H. and by the China Scholarship Council to J.W. and L.L.
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Conflict of interest
The authors declare that they have no conflict of interest.
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