Copper overload in the developing guinea pig liver: a histological, histochemical and biochemical study

Neonatal parenteral nutrition affects the metabolic flow of glucose in newborn and adult male Hartley guinea pigs' liver

Extremely premature birth is associated with a permanent disruption of energy metabolism. The underlying mechanisms are poorly understood. The oxidative stress induced by parenteral nutrition (PN) during the first week of life is suspected to reprogram energy metabolism in the liver. Full-term male Hartley guinea pigs (to isolate PN from prematurity) receiving PN enriched or not with glutathione (to isolate PN effects from PN-induced oxidative stress effects) or an Oral Nutrition (ON) during the first week of life were used. At 1 week (neonatal) and 16 weeks (adult), measurements of liver glutathione (GSH and GSSG) and activities of three key enzymes of energy metabolism (glucokinase (GCK), phosphofructokinase (PFK), and acetyl-CoA carboxylase (ACC)) were performed. Differences between groups were reported if p ≤ 0.05 (Analysis of Variance). At 1 week, compared to ON, PN induced higher GSSG (oxidative stress), higher GCK activity, and lower PFK and ACC activity, the glutathione supplement prevented all PN effects. At 16 weeks, early PN induced lower GSSG (reductive stress) and lower GCK activity, which was prevented by added glutathione, and higher ACC activity independent of glutathione supplement. ACC was negatively associated (r2 = 0.33) with GSSG. Increased nicotinamide adenine dinucleotide phosphate levels confirmed the glucose-6-phosphate accumulation at 1 week, whereas our protocol failed to document lipid accumulation at 16 weeks. In adult male guinea pigs, neonatal exposure to PN affected glutathione metabolism leading to reductive stress (lower GSSG) and an altered metabolic flow of glucose. Partial prevention with glutathione supplementation suggests that, in addition to peroxides, other factors of PN are involved.

Developmental changes in hepatic copper proteins in the guinea pig

We have suggested that Wilson's disease is caused by failure to adapt from the fetal to adult mode of copper metabolism and that the study of liver copper ontogeny might provide clues to the pathogenesis of Wilson's disease. This study traces the developmental changes in hepatic copper binding proteins in the guinea pig. During the last trimester, as fetal hepatic copper increases, metallothionein is the major copper binding peak in both the soluble and particulate supernatant fractions. After birth this peak decreases in parallel with the fall in liver copper. Metallothionein is absent from adult soluble supernatant and copper is associated with superoxide dismutase and a high molecular weight protein. A novel low molecular weight copper binding component is present in the particulate supernatant of neonatal liver, but is absent from the adult. Unlike many other animals, but similar to man, the switch from the fetal to adult mode of copper metabolism occurs at birth. Comparison of the copper protein profiles of the fetus and neonate with Wilson's disease are required to test the hypothesis that Wilson's disease is caused by developmental arrest of copper ontogeny.