The present invention relates to a method for enhancing arginase activity in a damaged or injured cell. In other aspects, the invention provides a method for treating a disorder that can be treated by enhancing arginase activity in a human in need thereof, the method comprising administering to the human an effective amount of a compound that enhances arginase activity. Such disorders include ischemia, hypoxia, neurodegenerative disease or condition, stroke or trauma of the nervous system. In yet another aspect, the invention provides methods for promoting regeneration of a neural cell in a human in need thereof.