Inter-Individual Variation in Levels of the Detoxifying Enzyme Glutathione S-Transferasepi(GSTP1) in Placentas from a Mexican Population

Abstract

Evidence indicates that fetuses and infants are more vulnerable to environmental toxicants than adults. The placenta is unique in that it is an organ that originates as a response to pregnancy. It is known that the placenta has detoxifying capabilities that may protect the fetus. Glutathione S-transferases (GSTs) catalyze the detoxifying reaction between glutathione and toxic chemicals and prevent binding of toxic compounds to DNA. Glutathione S-transferase pi (GST pi, GSTP1 gene) is the major GST enzyme found in the placenta, so levels of GST pi might therefore be important in protecting the fetus from toxic compounds. This study examines the levels of GST pi in the placenta from 51 consenting obstetric patients selected from a hospital in Tijuana, Mexico. GST pi was measured via Western blots of placental protein. There was a fourfold variability in placental GST pi levels between subjects; levels ranged from 2.73 to 11.29 µg/mg protein, with mean 5.55 µg/mg and geometric mean 4.54 µg/mg ± 0.96. There was a small positive correlation between GST pi levels and infant weight (r = .25, p = .040). This study provides novel information on inter-individual differences in protective enzyme levels found in placentas from a Mexican population.