The density of dopamine transporters or TH staining is reduced in the striatum of (G2019S) LRRK2 transgenic mice. (A) In-vivo 99mTc-TRODAT microSPECT imaging was performed to visualize the density of dopamine transporters in the striatum. The uptake of 99mTc-TRODAT is normal (red color scale) in the striatum (ST) of a wild-type mouse (d–f), but it is markedly reduced (green color scale) in a 12-month-old (G2019S) LRRK2 transgenic mouse (line 32) (g–i) (a–c: VOI definition of bilateral striatum and cerebellum (CB); d–i: fusion imaging of microCT and microSPECT; a, d, g: coronal section; b, e, h: sagittal section; c, f, i: horizontal section). (B) Compared with 12-month-old wild-type mice, specific uptake ratios of 99mTc-TRODAT were significantly reduced in (G2019S) LRRK2 transgenic mice at the same age. Each bar shows the mean±S.E. value of eight mice. *P<0.01. (C) Compared with 16-month-old control mouse or transgenic mouse expressing wild-type LRRK2 (line 43), density of TH-immunoreactive staining was decreased in the striatum of a (G2019S) LRRK2 mouse (line 32). (D) Optical density of striatal TH-positive terminals was significantly reduced in (G2019S) LRRK2 transgenic mice. Each bar represents the mean±S.E. value of four mice. *P<0.01