SHH and Parkinson disease: Intracerebral injection of SHH-N improves the motor function of rats with Parkinson’s disease and increases tyrosine hydroxylase immunoreactive neuron expression for the striatum, demonstrating that SHH possesses a specific treatment foreground against Parkinson’s disease, and SHH may be used as a potential therapeutic agent for neurodegenerative diseases (Dass et al., 2002).