VDR and Parkinson disease: Sirajo and colleagues applied the initial knowledge that the interaction between vitamins D3 and A is the result of an allosteric heterodimer complex formed between the vitamin D receptor and the retinoid X receptor [65], and that motor deficits in PD models can be ameliorated by vitamin D3 receptor stimulation with a vitamin D3 supplement [66] to evaluate Parkinsonism in a haloperidol mice model [44], which shows significant similarity with the rat models in terms of doses (1–10 mg/kg), route (mainly intraperitoneal), and duration (3–4 weeks).