TH and Parkinson disease: In the present study, we analysed the neuroprotective effects of β‐methylphenylalanine in an experimental model of rotenone‐induced PD in SH‐SY5Y cells and rats, and explored whether the neuroprotective effects exerted by β‐methylphenylalanine interfered with the depletion of tyrosine hydroxylase and mitochondrial dysfunction.