DISTRIBUTION OF CALCINEURIN A-BETA ISOENZYME MESSENGER-RNAS IN RAT-BRAIN - COMPARISON WITH THE DISTRIBUTION OF CALCINEURIN A-ALPHA ISOENZYME MESSENGER-RNAS

Using in situ hybridization histochemistry with specific antisense oli gonucleotides, we have studied the distribution of the beta subtypes o f the catalytic subunit (A) of calcineurin in rat brain. The predomina nt isoform, A beta 2, was found to be highly expressed in the hippocam pus, the medial habenula, the olfactory tubercle, the cortex and the c erebellar granular cell layer. Other brain areas showed only moderate to low A beta 2 mRNA signal intensities, High levels of the A beta 3 i soform were only found in the granular cell layer of the cerebellum an d the reticular formation. In all the other brain structures examined, the A beta 3 isoform was expressed at lower levels than the A beta 2 subtype. No A beta 1 mRNA was detected under the assay conditions used . In contrast to the clear-cut regional differences in the distributio n of the mRNA's for the calcineurin A alpha 1 and A alpha 2 isoform in rat brain, no difference could be detected in the distribution patter n of the mRNA's for calcineurin A beta 2 and A beta 3.