GHSR and Parkinson disease: In vivo, multiple independent studies in the MPTP rodent model of PD have shown that AG binds to GHS-R1α and activates SNpc dopaminergic neurons, rescues from neuronal death and prevents the depletion of dopamine in the striatum (Jiang et al., 2008; Andrews et al., 2009a; Moon et al., 2009a).