Figure 5.

IP6K2 and 4.1N expressed in the granule cells of cerebellum affect Purkinje cell morphology and parallel fiber–Purkinje cell synapses. A, Purkinje cell volume, spine number, and spine density were significantly decreased in IP6K2-KO mice when compared with their WT counterparts. (top, 60× magnification; bottom, 100× magnification). B, Immunostaining of VGlut1/calbindin and VGlut2/calbindin in cerebellar Purkinje cells from WT and IP6K2-KO mice showed that the density of VGlut1 was markedly reduced in IP6K2-KO mice, indicating that knock-out mouse brain sections contained fewer parallel fiber–Purkinje cell synapses compared with WT mouse brain. However, there was no difference in the climbing fiber–Purkinje cell synapses of IP6K2-KO mouse cerebellum compared with wild type. Scale bar, 20 μm. C, Electron microscopic analysis of the cerebellar molecular layer from IP6K2-KO mouse brain (8 weeks old) also revealed fewer synapses compared with WT mouse brain. However, the ultrastructure of synapses in the cerebellum was relatively normal in the IP6K2-KO. Scale bar, 500 nm. Data were statistically analyzed by paired Student's t test. Significant differences (***p < 0.001, **p < 0.01) were observed in comparison with wild-type controls. Data are presented as the mean ± SD and are representative of three independent experiments performed under identical conditions. Golgi staining of IP6K2-knockout (KO) mice cerebellum with no significant morphological changes in pyramidal cells, granule cells, stellate cells and Golgi cells when compared to their wild-type (WT) counterparts, as shown in Figure 5-1.