Novel roles for neurotrophins are suggested by BDNF and NT-3 mRNA expression in developing neurons.
The results of our in situ hybridization experiments demonstrate that sensory neurons, sympathetic neurons, and motoneurons express brain-derived neurotrophic factor and/or neurotrophin-3 mRNAs during development in mouse. In accordance with previous data, we also find neurotrophins in the targets of sensory neurons (skin) and motoneurons (muscle) and the neurotrophin receptors p75, trkA, and trkB in sensory and sympathetic ganglia. These results suggest that neurotrophins have roles other than being target-derived factors that support neuron survival during developmental cell death (neurotrophic hypothesis), but may be transported in an orthograde fashion in neurons and released from axon terminals. We discuss several novel roles for neurotrophins, including autocrine/paracrine regulation of neuron survival, regulation of Schwann cell activity, and neuron to target signaling.
Department of Physiology and Biophysics, University of Washington, Seattle 98195.
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Schecterson
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Bothwell
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor; D005728:Ganglia, Sympathetic / Q000196:embryology / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009046:Motor Neurons / Q000378:metabolism; D009132:Muscles / Q000196:embryology / Q000378:metabolism; D009414:Nerve Growth Factors / Q000235:genetics* / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D009475:Neurons, Afferent / Q000378:metabolism; D020933:Neurotrophin 3; D012333:RNA, Messenger / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D017475:Receptors, Nerve Growth Factor; D014158:Transcription, Genetic
D019208:Brain-Derived Neurotrophic Factor; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D020933:Neurotrophin 3; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017475:Receptors, Nerve Growth Factor