The neurotrophins NGF, BDNF, NT-3, and NT-4/5 promote the survival of neurons following environmental, toxic, and infectious injuries and are therefore considered to have outstanding therapeutic potential in the prevention and treatment of neuropathies and neurodegenerative diseases. the production of endogenous neurotrophins is dynamically regulated at the level of transcription. These mechanisms represent a target for rational drug design. In the previous period of this proposal we studied neurotrophin gene transcription in senescent WI-38 cells. The results of these experiments revealed that cellular senescence does not affect neurotrophin gene transcription. We therefore initiated an alternative approach. We focused on zebrafish BDNF. Zebrafish BDNF was cloned. The encoded BDNF was 91% identical with human NGF.BDNF transcripts were found int he zebrafish retina, brain, ear, neuromast, fin, and cloaca. Injection of BDNF antisense oligonucleotides into embryos induced a sunken lens phenotype. histological analysis revealed selective cell death in the retina, brain, and spinal cord. We hypothesize based on these data that BDNF regulates neuron survival in the zebrafish. The present proposal will further examine this hypothesis. We will address the following questions (1) which cells die in response to BDNF deprivation (2) how do they die and (3) are the survival effects of BDNF age-dependent. These questions will be addressed using antisense oligonucleotides, specific anti-BDNF antibodies, immunocytochemistry, in situ hybridization, histology, and stains for apoptotic cells.
