GHRL and Parkinson disease: Other studies indicate that ghrelin modulates dopaminergic neurons in the ventral tegmental area (VTA) and SN (Stievenard et al., 2017) and induces a neuroprotective effect in animal models of PD (Bayliss and Andrews, 2013; de Candia and Matarese, 2018; Morgan et al., 2018).