Fig. 3: Depletion of dopamine neurons with 6-OHDA or MPTP in mice increases numbers of DAT⁺ and TH⁺ PBMCs and treatment with L-DOPA+ Benserazide restores baseline levels. Treatment with L-DOPA alone restored DAT⁺ but not TH⁺ PBMCs.

A Schematic of experimental design using toxin-induced lesions. B Animals were grouped by treatment conditions as shown. C, D Bilateral infusion of 6-OHDA (5 mg/mL) into the median forebrain bundle, or acute depletion by four i.p. MPTP injections (E, F) reveal that PD-like lesions in mice reproduce the phenomena observed in Parkinson’s patients and healthy controls. C, E Both TH+ and DAT+ cells are increased following dopamine neuron depletion with 6-OHDA (C) or MPTP (E). TH+ and DAT+ cells are restored to, or trend towards, healthy levels following treatment with L-DOPA+ AADC inhibitor Benserazide. In both PD models, TH-expressing cells are reduced to near-healthy levels following LDOPA treatment alone, while DAT-expressing cells are reduced to healthy-levels only with L-DOPA+ Benserazide, suggesting separate regulatory steps for DAT and TH expression in peripheral immune cells. D, F Total myeloid cells, defined by CD11b expression, are not changed amongst treatment groups in either model. All data shown are ±SEM.