Inositol 1,4,5-triphosphate receptor protein immunohistochemistry of cerebellar Purkinje cells in two dogs with hypoglycemia

Immunohistochemical study was performed on cerebellar Purkinje cells of two dogs with hypoglycemia using an antibody against the inositol 1,4,5-triphosphate receptor that is identical to the cerebellar Purkinje cell glycoprotein P(400) (P(400)/InsP(3)R). In the cerebellar neocortex of an acute case of hypoglycemia, the P(400)/InsP(3)R staining of hypoglycemic Purkinje cells was heterogeneous: some peripheral dendrites, including spiny branchlets, were negative and others were stained with various intensities, although Purkinje cells were morphologically intact by hematoxylin and eosin (HE) stain. In a chronic case of hypoglycemia, almost all the dendrites of Purkinje cells of both the neo- and archicortex of the cerebellum were not stained with the P(400)/InsP(3)R antibody. This is in contrast to the normal dog where Purkinje cell bodies, axons, and dendrites, including spiny branchlets, are intensely stained by the P(400)/InsP(3)R antibody. These results suggest that P(400)/InsP(3)R immunolabeling of Purkinje cells decreased, despite their morphology being preserved by HE stain, and that the function of P(400)/InsP(3)R, especially in spiny branchlets that receive inputs originating from axon terminals of parallel fibers, may be impaired in hypoglycemia.