BDNF promotes target innervation of <it>Xenopus </it>mandibular trigeminal axons <it>in vivo</it>

• Main Authors: Ishibashi Shoko, Dorey Karel, Huang Jeffrey K, Amaya Enrique
• Format: Article
• Language: English
• Published: BMC 2007-05-01
• Series: BMC Developmental Biology
• Online Access: http://www.biomedcentral.com/1471-213X/7/59

<p>Abstract</p> <p>Background</p> <p>Trigeminal nerves consist of ophthalmic, maxillary, and mandibular branches that project to distinct regions of the facial epidermis. In <it>Xenopus </it>embryos, the mandibular branch of the trigeminal nerve extends toward and innervates the cement gland in the anterior facial epithelium. The cement gland has previously been proposed to provide a short-range chemoattractive signal to promote target innervation by mandibular trigeminal axons. Brain derived neurotrophic factor, BDNF is known to stimulate axon outgrowth and branching. The goal of this study is to determine whether BDNF functions as the proposed target recognition signal in the <it>Xenopus </it>cement gland.</p> <p>Results</p> <p>We found that the cement gland is enriched in BDNF mRNA transcripts compared to the other neurotrophins NT3 and NT4 during mandibular trigeminal nerve innervation. BDNF knockdown in <it>Xenopus </it>embryos or specifically in cement glands resulted in the failure of mandibular trigeminal axons to arborise or grow into the cement gland. BDNF expressed ectodermal grafts, when positioned in place of the cement gland, promoted local trigeminal axon arborisation <it>in vivo</it>.</p> <p>Conclusion</p> <p>BDNF is necessary locally to promote end stage target innervation of trigeminal axons <it>in vivo</it>, suggesting that BDNF functions as a short-range signal that stimulates mandibular trigeminal axon arborisation and growth into the cement gland.</p>