Objective: To evaluate, in rat offspring, bone changes induced by excess maternal thyroxin during pregnancy and lactation, and to assess the reversibility of these changes after weaning. Material and methods: Twenty Wistar rats were distributed in two groups, hyperthyroid and control, that were treated daily with L-thyroxin (50 mcg/animal) and placebo, respectively. The treatment was initiated seven days before mating and continued throughout pregnancy and lactation. From every female of each of the two groups, two offspring were euthanized after birth, two at 21 days of age (weaning), and two at 42 days of age (21 days after weaning). In newborns, the length of pelvic and thoracic limbs were measured, and in the other animals, the length and width of the femur and humerus were measured. Bones were dissected, decalcified, embedded in paraffin, and analyzed histomorphometrically. Results: Excess maternal thyroxin significantly reduced the length of the pelvic limb in neonates. In 21-day-old individuals, excess maternal thyroxine reduced the length and the width of the femur and the humerus. It also increased thickness of the epiphyseal plate and the percentage of trabecular bone tissue. In 42-day-old individuals, there were no significant differences between groups in relation to the parameters evaluated in the previous periods. Conclusion: Excess maternal thyroxine reduced growth in suckling rats both at birth and at weaning, and it also increased the percentage of trabecular bone tissue in 21-day-old animals. These changes, however, were reversible at 42 days, i.e., 21 days after weaning. Arch Endocrinol Metab. 2016;60(2):130-7

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.

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