Co-60 and Ca-45 autoradiography in cerebral ischemia in the rat

Radioisotopes of divalent Co (Co-57 in Single photon emission tomography (S PECT)and Co-55 in positron emission tomography (PET) have clinically been a pplied to visualize Ca related brain damage. The cerebral uptake of Ca-45 a nd Co-60 in a unilateral stroke model in the rat was compared; 100 mu Ci (C aCl2)-Ca-45 or 60 mu Ci (CoCl2)-Co-60 was intravenously given at day 2 or 9 and the rats were killed 24 h later for autoradiography. Similarly increas ed uptake of Ca-45 and Co-60 was observed at both time points in unilateral ly affected areas such as the cerebral cortex, dentate gyrus, caudate putam en of the striatum, substantia nigra pars reticulatum and corpus geniculatu m. More Ca-uptake was found in the hippocampus CA1 region (at day 10) and t he thalamus (ventral part at both time points). Radioactive Co but not Ca a ccumulated in the choroid plexus. Although the present investigation suppor ts the idea that divalent Go-isotopes are useful to visualize stroke induce d damage and choroid plexus function, these radionuclides do, however, not allow to detect excessive Ca-influx in degerating neurones. (C) 1998 Elsevi er Science Ireland Ltd. All rights reserved.