Dopaminergic system markers in the striatum and mesencephalon. (A) Immunoblot analysis of striatum/mesencephalon samples revealed a significant overall increase in the amount of tyrosine hydroxylase (THase) in Ctsk-/- mice (n = 10) as compared to WT controls (n = 13). A representative immunoblot is shown in the lower panel; lanes represent separate individuals. (B) ELISA results from the same tissue lysates showed an average increase of 40% in the amount of dopamine in Ctsk-/- mice. (C) Immunoblot analysis further indicated that levels of dopamine type 2 receptors (D2R) were significantly increased by approximately 30% in Ctsk-/- mice. (D, E) THase immunolabeling of the VTA. At identical intensity gain settings, confocal fluorescence microscopy on horizontal brain sections labeled with an antibody against THase, resulted in an intense specific staining of the VTA of Ctsk-/- mice, as compared to the moderate signal observed in the same region of WT brain sections. (F) Fluorescence intensity analysis of THase immunolabeled brain sections revealed a significant increase in THase intensity in Ctsk-/- compared to WT mice. Bars - 200 μm. Levels of significance are denoted as ** for p < 0.01; *** for p < 0.001.