Postnatal gender-dependent maturation of cellular cysteine uptake.
BACKGROUND
In view of the functional capacity of glutathione synthesis in premature infants, and because the availability of cysteine is one the rate limiting steps in glutathione synthesis, we hypothesized that the low glutathione levels in premature infants may be due to immaturity of the active cellular uptake of cysteine.


OBJECTIVE
To document in cells from newborn infants the effect of maturity and gender on cysteine uptake and consequently on glutathione levels.


METHODS
Incorporation of L-[35S] cysteine was measured in leukocytes from cord blood and from tracheal aspirates (TAC) of newborn infants of varying (gestational as well as postnatal) ages and gender. Cysteine uptake was correlated with glutathione in TAC.


RESULTS
The maturity of newborn girls positively influences cysteine uptake, which is responsible for 78% of the variation in their glutathione content. However, in newborn boys, gestational and postnatal ages did not influence the cysteine uptake.


CONCLUSIONS
Cysteine uptake appears to be the limiting step explaining the reported gender-related differences in glutathione as well as the low levels of this central antioxidant found in premature infants. The immature cysteine uptake found in cells from premature infants raises questions about the bioavailability of this conditionally essential amino acid in regimens of parenteral nutrition for human neonates.
Lavoie
Jean-Claude
JC
Research Centre and Neonatal Service, Hĵpital Ste-Justine, Montreal, Que, Canada. jclavoie@justine.umontreal.ca
Rouleau
Thérèse
T
Truttmann
Anita C
AC
Chessex
Philippe
P
D000367:Age Factors; D000975:Antioxidants / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism* / Q000493:pharmacokinetics*; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005865:Gestational Age; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D012737:Sex Factors; D013997:Time Factors; D014132:Trachea / Q000378:metabolism
D000975:Antioxidants; D005978:Glutathione; D003545:Cysteine