Conservation of localization patterns of IP3 receptor type 1 in cerebellarpurkinje cells across vertebrate species

The distribution of inositol 1,4,5-trisphosphate (IP3) receptor type 1 (IP( 3)R1) protein was studied in the adult cerebella of six different vertebrat e species, zebrafish, skate, claw frog, rat, hamster, and mouse. The recept or was found at high expression levels in Purkinje cells in all species exa mined using a subtype-specific polyclonal antiserum against IP(3)R1 and flu orescence immunocytochemistry. The immunoreactivity for IP(3)R1 was found i ntracellularly at high concentrations in dendrites and somata and at lower levels in axons of these cells. Despite the morphological and functional di fferences of the cerebella the staining patterns of IP(3)R1 labeling in Pur kinje cells was preserved. This is notable because the cerebella were taken from organisms representing a large segment of vertebrate phylogenetic dev elopment. The high expression levels of IP(3)R1 in Purkinje cells were foun d independent of the degree of the formation of fissures and folia and of t he degree of branching of Purkinje cell dendrites. The conservation of cere bellar structures not only at the cellular level but more importantly at th e molecular level suggests that identical intracellular calcium signaling m echanisms are used in a number of species that represent different areas of phylogenetic development and specialization. (C) 2000 Wiley-Liss, Inc.