Figure 3.

(A) Coronal sections of brain from GIRK2 +/+ and −/− mouse brains stained with antibodies against the N terminus of GIRK2, the N terminus of GIRK1, and the C terminus of IRK1 show that there is no detectable GIRK2 and dramatically reduced GIRK1 immunoreactivity in the GIRK2 −/− mice. The IRK1 staining patterns are the same for these mice. CTX, cerebral cortex; HP, hippocampus; Th, thalamus. (Bar = 10 mm.) (B) Sagittal views of cerebella from GIRK2 +/+ and −/− mice stained with the antibodies described in A. Although there is no detectable GIRK2 protein in the −/− mice, there is still significant GIRK1 staining, whereas the level of IRK1 expression appears to be the same. g, granule cell layer; m, molecular layer. (Bar = 20 mm.) (C) Coronal sections of ventral midbrain from +/+, −/−, wv/−, and wv/wv mice are stained with antibodies against TH and the N terminus of GIRK2. The TH staining of +/+, −/−, and wv/− midbrain appears similar, whereas there are fewer TH-positive neurons in the substantia nigra pars compacta (SNc) of the wv/wv midbrain. GIRK2 immunoreactivity is absent in the −/− midbrain but can still be found in the wv/− and wv/wv mice, although the dendritic staining is dramatically reduced. SNr, substantia nigra pars reticulata; VTA, ventral tegmental area. (Bar = 1 mm.) (D) High magnification views of parasagittal cerebellar sections from +/+, −/−, wv/−, and wv/wv mice. The sections are counterstained with toluidine blue or stained with antibody against the C terminus of IRK1, which stains the cell body and dendrites of the Purkinje cells as well as the dendrites in the granule cell layer. The wv/− cerebellum is mostly wild-type in appearance except for regions with a Purkinje cell layer more disorganized and broader than that in GIRK2 +/+ and −/− mice. Some Purkinje cells and their dendrites can be found in the granule cell layer of wv/− mice. In the wv/wv cerebellum, there is no granule cell layer, and the Purkinje cells with disorganized dendrites are scattered throughout the cerebellum. m, molecular layer; p, Purkinje cell layer; g, granule cell layer; p/g, cell layer where both Purkinje cells and granule cells are found; m/p, cell layer where molecular layer and Purkinje cell layers collapse into one in the absence of granule cell layer; wm, white matter. (Bar = 0.2 mm.)