Effect of galactose toxicity on growth of the rat fetus and brain.

Abstract

Extract: In pregnant albino rats fed a diet containing 40% galactose, sugar crossed the placenta and was found in the blood, urine, and amniotic fluid of the fetuses. Galactose-1-phosphate was also found in fetal brain tissue. The fetus of galactose-fed rats weighed 5 to 12% less than the fetus of control rats fed a diet of similar composition, but containing no galactose. Growth retardation was reversible. Fetuses of rats fed the galactose diet during the first half of pregnancy were less retarded than were those of rats fed galactose throughout pregnancy or during the second half of pregnancy only. Body weight of animals at 10 weeks of age did not differ significantly from that of control animals. In the galactosemic fetus, the reduction in brain weight was approximately equal to that in body weight. In galactosemic fetuses, the content of DNA in brain was less than that in control animals, indicating a reduction in cell number. In a group of preterm fetuses 18 days of gestation, total protein content in brain was also reduced when compared with that of controls, suggesting a reduction in cell size. Brains of galactosemic fetuses at term, however, contained normal amounts of protein. Offsprings of galactose-fed rats examined at three and ten weeks of age had smaller brains than offsprings of control animals, but total DNA content was normal, indicating normal cell number. These findings indicate that galactose toxicity is exhibited in the fetal rat by retardation in body growth. Brain growth is also affected, apparently as a result of interference with cell replication and, perhaps to some extent, with cell growth. Speculation: Although it is as yet unknown whether exposure of human fetuses to high concentrations of galactose affects growth of the brain, clinical observations suggest that it may do so. Mental performance of galactosemic children is at times subnormal despite early treatment with a galactose-free diet. Evidence is accumulating which suggests that mothers known to be heterozygous for the galactosemia gene should be treated with a diet low in lactose during pregnancy.