C Loriette's scientific contributions

Hepatic cystathionase and cysteine sulfinate decarboxylase activities are drastically affected by cholic acid added to the diet without cholesterol. When cholic acid and cholesterol are given together, only cysteine sulfinate decarboxylase activity is changed. Neither kidney enzyme activity nor taurine concentrations in the liver and kidney are noticeably modified, whatever the diet.

Although various physiological roles were suggested for taurine in different tissues like brain, heart, retina, the origin of this substance in these tissues is still unclear. Taurine could be provided by the diet and could also be synthesized. Until now, three main pathways were described or postulated in mammals for this biosynthesis 1: the “inorganic pathway” untilizing inorganic sulfate, the “cysteamine pathway”, the “cysteine sulfinic pathway”.

Activities of cysteine dioxygenase (CO) and cysteine sulfinate decarboxylase (CSD) and the concentrations of taurine (T) in brain, liver and kidney of rats fed on diets containing 18% casein (A), 60% casein (B) and 17% casein supplemented with 1% of taurine (+T), were measured. Regardless of the diet, the three measurements were the same in the brains of the animals in the three groups. In the liver and the kidney, CO activity was also the same in all three diets, but a decrease of CSD activity associated to an increase of T was observed in rats fed on diet B. The taurine-supplemented diet led to an increase in T concentration.

Activities of cysteine dioxygenase (CO) and cysteine sulfinate decarboxylase (CSD) and the concentrations of taurine (T) in brain, liver and kidney of rats fed on diets containing 18% casein (A), 60% casein (B) and 17% casein supplemented with 1% of taurine (+T), were measured. Regardless of the diet, the three measurements were the same in the brains of the animals in the three groups. In the liver and the kidney, CO activity was also the same in all three diets, but a decrease of CSD activity associated to an increase of T was observed in rats fed on diet B. The taurine-supplemented diet led to an increase in T concentration.Copyright © 1979 S. Karger AG, Basel

The patterns of development of cysteine oxidase (CO) and cysteine sulfinic acid decarboxylase (CSD) in rat liver are not similar. It was observed that CO is not under sex control as CSD is. The results obtained agree with the idea that, in liver, as well as in brain, CSD is the limiting factor for the regulation of taurine biosynthesis.

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.