The first study based on a sub-acute MPTP-induced mouse model of PD demonstrated that ghrelin-mediated neuroprotection might be related to a reduction in caspase-3-mediated apoptosis via the regulation of gene expression of Bcl-2 and Bax in the DA neurons in SN (Jiang et al., 2008). This evidence concerns the gene CASP3 and Parkinson disease.