CARBONIC-ANHYDRASE-II AND CARBONIC ANHYDRASE-RELATED PROTEIN IN THE CEREBELLAR CORTEX OF NORMAL AND LURCHER MICE

The developmental profiles of carbonic anhydrase II (CA-II) and a carb onic anhydrase related protein (CARP) were studied in rat and mouse ce rebella. Enzyme histochemistry, immunohistochemistry, in situ hybridis ation and Western blotting were used to study the synthesis and expres sion of these enzymes in cerebellar sections from age matched control, CA-II deficient and lurcher mice, the latter being characterised by P urkinje cell degeneration. Both CA-II and CARP were first found to be expressed in the Purkinje cells in the 9 day old mouse, and the immuno reactivity of both peptides increased with time. Immunohistochemistry showed more intense staining of CARP than of CA-II in Purkinje cells t hroughout the developmental profile of the mouse, and this was mirrore d by the mRNA levels determined by in situ hybridisation. Immunohistoc hemistry of CA-II and CARP also demonstrated the progressive dendritic growth of the mouse and rat Purkinje cells. CA-II and CARP immunoreac tivity ceased by the end of cerebellar maturation. The onset of Purkin je cell degeneration was detected at day 10 in the lurcher mouse, with concomitant marked decrease in CA-II level: however CARP expression w as found to be unchanged. By postnatal day 16 neither CA-II mRNA, prot ein, nor activity was detectable in contrast to CARP which remained at a decreased level until the Purkinje cell population had completely d egenerated. Our findings suggest a role of CA-II in the degenerative p rocesses of the lurcher Purkinje cells, with CARP playing an important role in the development and maturation of the cerebellar cortex.