Motoneuron injury and degeneration are important medical issues, with thousands of people diagnosed with spinal motoneuron diseases, spinal cord injuries, and peripheral nerve injuries every year. The long-term goals of this proposal are to contribute to our understanding of the motoneuron's cellular and molecular response to injury. Using a variety of molecular neuroscience techniques, I will study the relationship of steroid hormones to a novel protein (neuritin) thought to be involved in the ability of neurons to change their overall shape, and therefore their functional connectivity. Additionally, I will examine the relationship between steroid hormones and the immune system in promoting neuronal survival in the central nervous system following axonal injury. Techniques to be used include in situ hybridization, immunocytochemistry, electron microscopy, and the use of transgenic mice. This research could potentially lead to future treatment strategies for traumatic nerve injuries and neurodegenerative diseases. [unreadable] [unreadable]