Regional and subcellular distribution of taurine-synthesizing enzymes in the rat central nervous system

Abstract

The distribution of cysteine oxidase (CO) and cysteine sulfinate decarboxylase (CSD) was examined in 12 regions of the rat central nervous system (CNS). The distribution of CO activity, expressed as μmol of cysteine sulfinate formed per h per g, was the following: hypothalamus, superior and inferior colliculi, 94–99 μmol/h/g; olfactory bulbs, cerebral cortex, striatum, and hippocampus, 44–51 μmol/h/g; cerebellum, 71 μmol/h/g; pons-medula and spinal cord, 94 and 60 μmol/h/g, respectively. The distribution of CSD activity expressed as μmol of cysteine sulfinate decarboxylated per h per g was the following: hypothalamus and colliculi, 14–21 μmol/h/g; olfactory bulbs, cerebral cortex, striatum, hippocampus, and cerebellum, 8–13 μmol/h/g; pons-medulla, 7.3; and spinal cord, 3.6 μmol/h/g. No CSD activity was detected in sciatic nerve. The subcellular distribution of CO and CSD activities was studied in hypothalamus, colliculi, and cerebral cortex. CO activity was localized in synaptosomes, mitochondria, and microsomes. CSD was primarily confined to the crude mitochondrial fraction and after subfraction, recovered mainly in the synaptosomal fraction.