Changes in Cysteine Dioxygenase and Cysteinesulfinate Decarboxylase Activities and Taurine Levels in Tissues of Pregnant or Lactating Rat Dams and Their Fetuses or Pups

Abstract

The level of taurine and the activities of the two enzymes involved in its synthesis, cysteine dioxygenase and cysteinesulfinate decarboxylase, were measured in tissues of rat dams during pregnancy and lactation and in their fetuses or pups. The most marked changes observed in the dams included an increased hepatic taurine concentration in late pregnancy (20 days), a decreased plasma taurine concentration during late pregnancy and throughout lactation, and a decrease in tissue cysteine dioxygenase activity in late lactation (20 days). These observations suggest that the dam’s taurine pools may be an important source of taurine for secretion in the milk and that pregnant dams may prepare for the onset of lactation by accumulating additional taurine in the liver. There was little if any correlation between the activities of either of these key enzymes in taurine synthesis and tissue taurine levels. The taurine concentrations in liver, brain, heart and plasma of the young decreased between 1 day before birth and 20 days of age. Cysteine dioxygenase and cysteinesulfinate decarboxylase specific activities increased in the brains of pups between birth and 20 days of age, and cysteinesulfinate decarboxylase activity increased in the livers of pups between birth and 20 days of age. Cysteinesulfinate decarboxylase activity in 80-day-old male rats was more than six times that in female littermates, but no effects of sex on cysteine dioxygenase activity or tissue taurine concentrations were observed.

Effect of Taurine in Rat Milk on the Growth of Offspring.

“…It has been demonstrated that the liver is the main organ of taurine synthesis [16] and that the milk taurine level is positively correlated with hepatic taurine concentration during the lactational period [26]. The hepatic taurine may serve as a source of taurine for secretion into the milk.…”

Roles of taurine-mediated tonic GABAA receptor activation in the radial migration of neurons in the fetal mouse cerebral cortex

“…Taurine is an endogenous partial agonist of the GABA A R and induces chloride currents in neurons (Linne et al, 1996; Ye et al, 1997). Although the capacity to synthesize taurine is low during fetal life (Hayes and Sturman, 1981; Kuo and Stipanuk, 1984; Ghisolfi, 1987), taurine levels are higher in the immature brain than in the adult brain (Kaczmarek, 1976; Benitez-Diaz et al, 2003). In mammals, sufficient taurine for embryonic development is received from the mother via the placenta, while neonates obtain taurine from their mothers’ milk (Sturman et al, 1977; Sturman, 1981).…”

Enhanced Uptake of Taurine by Basolateral Plasma Membrane Vesicles Isolated from Developing Rat Liver

“…The biosynthesis of taurine is decreased in most developing mammals due to reduced activity of the rate-limiting enzyme, cysteine sulfinic acid decarboxylase (5,16). Although measurement of in vitro enzyme activity may not accurately reflect in vivo biosynthetic rates, the decreased CSAD activity observed during development implies that exogenous sources of taurine play an important role in maintenance of tissue stores (6).…”

“…During development, maintenance of intrahepatic taurine stores could be of particular importance inasmuch as bile flow is already diminished and exposure to oxidant stress is increased (1 1, 2 1, 22). In addition, taurine biosynthesis and the capacity of the kidney to retain taurine are decreased in the immature animal (5,16,23). Under these conditions, an efficient transport system for taurine uptake from portal blood might prevent intracellular depletion of this p-amino acid.…”