Conservation of localization patterns of IP(3) receptor type 1 in cerebellar Purkinje cells across vertebrate species.

The distribution of inositol 1,4,5-trisphosphate (IP(3)) receptor type 1 (IP(3)R1) protein was studied in the adult cerebella of six different vertebrate species, zebrafish, skate, claw frog, rat, hamster, and mouse. The receptor was found at high expression levels in Purkinje cells in all species examined using a subtype-specific polyclonal antiserum against IP(3)R1 and fluorescence immunocytochemistry. The immunoreactivity for IP(3)R1 was found intracellularly at high concentrations in dendrites and somata and at lower levels in axons of these cells. Despite the morphological and functional differences of the cerebella the staining patterns of IP(3)R1 labeling in Purkinje cells was preserved. This is notable because the cerebella were taken from organisms representing a large segment of vertebrate phylogenetic development. The high expression levels of IP(3)R1 in Purkinje cells were found independent of the degree of the formation of fissures and folia and of the degree of branching of Purkinje cell dendrites. The conservation of cerebellar structures not only at the cellular level but more importantly at the molecular level suggests that identical intracellular calcium signaling mechanisms are used in a number of species that represent different areas of phylogenetic development and specialization. Copyright 2000 Wiley-Liss, Inc.