Effects of maternal hyperphenylalaninemia on fetal brain development: a biochemical study

Effects of 60 Hz electric and magnetic fields on maturation of the rat neopallium

This study was undertaken to determine the effects of extremely low frequency (ELF; 60 Hz) electromagnetic (EM) fields on somatic growth and cortical development, as well as biochemical and morphological maturation, of the rat neopallium. On the fifth day of pregnancy, female rats were put in pairs into plastic cages that were housed in a specially constructed apparatus for irradiation under three separate sets of combination and intensity: 1) 1 kV/m and 10 gauss; 2) 100 kV/m and 1 gauss; and 3) 100 kV/m and 10 gauss. The dams were exposed for 23 h daily, from days 5 through 19 postconception, after which they were returned to cages outside the exposure apparatus until they littered. The neonates were culled to eight pups per litter. At 0 (birth), 5, 12, and 19 days postnatally, they were killed for biochemical and morphological studies. Another group of pregnant rats was sham-exposed in an identical apparatus, which was not energized, and the pups were used as controls. The irradiated rats exhibited no physical abnormalities, nor did they show brain deformities such as swelling or herniation following exposure to ELF-EM fields. There was no difference in somatic growth between control and exposed rats, but a small reduction in cortical weight was observed in rats exposed at 1 kV/m and 10 gauss, and 100 kV/m and 1 gauss, respectively. Biochemical measurements of DNA, RNA, protein, and cerebroside concentrations indicated that among the three separate exposures, only the neopallium of rats exposed at 1 kV/m and 10 gauss showed a small reduction in DNA level, as well as small reductions in RNA and protein levels. No changes were noticed in cerebroside levels in any exposed animals, and there were no differences in protein/DNA and cerebroside/DNA ratios between control and exposed rats. Morphological observations did not reveal any detectable alterations in the irradiated rats. These results indicate that exposure to ELF-EM fields caused minimal or no changes in somatic growth and cerebral development of the rat.

Effects of 60 Hz electric and magnetic fields on the development of the rat cerebellum

The effects of extremely low frequency (ELF) electromagnetic (EM) fields on the maturation of the rat cerebellum were studied. Newborn rats were exposed to 60 Hz electric and magnetic fields under three different combinations in a specially constructed apparatus. The pups were irradiated for 7-8 h daily, with a 30-min interruption for nursing. Pups were kept with their mothers for the remainder of the time. After approximately 1, 2, or 3 weeks of exposure, the pups were killed. Control pups were sham exposed. The somatic growth of the irradiated rats did not show any significant difference from sham-exposed controls. At 1 kV/m and 10 gauss exposure, there was a small but statistically significant decrease in cerebellar mass. In rats exposed at 1 kV/m and 10 gauss, DNA and RNA levels were significantly higher than those in sham-exposed controls at 6 and 13 days of age, but at 20 days, these two biochemical constituents were similar in both groups of rats. The ELF-EM treatment had no effect on protein and cerebroside concentrations. In terms of age effects, DNA and RNA exhibited increases from 6 to 13 days of age, and declined from 13 to 20 days. Protein and cerebroside levels exhibited increases during the 6-20-day periods. In rats exposed at 100 kV/m and 1 gauss, the DNA levels were initially less than those of sham-exposed controls at 8 days of age, reached approximately the same levels at 14 days, and then were higher than those of controls at 22 days. There was, therefore, a significant ELF-EM effect as well as a significant interaction between age and ELF-EM exposure. In terms of age effects, DNA levels for both control and exposed animals increased from 8 to 14 days. From 14 to 22 days, DNA levels of exposed rats continued to increase while those of the controls decreased. This age effect was significant. RNA levels in both groups of animals showed increases from 8 to 14 days of age, but the increase was less for the irradiated animals than for the controls. From days 14 to 22, RNA levels for both groups showed a reduction, but the decrease was greater in the irradiated than in control rats. ELF-EM treatment significantly reduced protein levels at 8 days of age, but at 14 to 22 days, protein levels of exposed rats were higher than those of controls.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of phenylalanine loading on protein synthesis in the fetal heart and brain of rat: an experimental approach to maternal phenylketonuria

Pregnant rats were loaded with L-phenylalanine, and the distributions of [14C]leucine and [14C]urea into fetal plasma and tissues were examined. Uptake of [14C]leucine into the supernatant and protein fractions of fetal plasma and tissues was low in the rats loaded with phenylalanine. In contrast, [14C]urea was distributed identically in both groups, indicating that maternal hyperphenylalaninemia did not affect blood flow across the placenta. Administration of phenylalanine and p-chlorophenylalanine produced amino acid imbalance in fetal tissues. Along with these changes, polysomes of the affected fetal heart and brain disaggregated without changes in the ribonuclease activity. These results indicate that high phenylalanine levels in maternal plasma disturb the active transport of amino acids across the placenta, causing an amino acid imbalance and disaggregation of polysomes in fetal heart and brain. These changes may contribute to the congenital heart disease and mental retardation of maternal phenylketonuria.

Maternal phenylketonuria-chronology of the detrimental effects on embryogenesis and fetal development: pathological report, survey, clinical application

Maternal phenylketonuria (PKU) is likely to have detrimental effects on embryogenesis and fetal development. Manifestations in the offspring include spontaneous abortion, various congenital malformations, intrauterine growth retardation, and microcephaly. The time at which the metabolic abnormalities induce pathologic embryogenesis can be documented by knowing the time of the development of specifically damaged organ systems. This review reveals that, while the most recognized congenital malformations occur in the heart, the most common abnormality is growth inhibition occurring throughout pregnancy. The organ system most commonly affected by this growth inhibition is the brain, resulting in a high incidence of micrencephaly. It appears that maternal phenylketonuria interferes with appropriate fetal growth and that this effect occurs during the entire course of pregnancy and has no tissue specificity. This information can be both informative to pathologists and useful to clinicians.

Cerebral biochemical abnormalities in experimental maternal phenylketonuria: gangliosides and sialoglycoproteins

The present study sought a biochemical explanation for retarded brain development in the heterozygous offspring of the phenylketonuric (PKU) mother. Two rat models of simulated maternal PKU, one induced by p-chlorophenylalanine and phenylalanine and the other by phenylacetate, were employed in this investigation. Maternal PKU had no influence on cerebral concentrations of DNA, protein, and cholesterol, which were normal in the 2 d old pup. However, there was a noticeable disruption of the normal ganglioside pattern and a significant reduction of sialoglycoproteins. Concomitant with a delayed drop in the gangliosides Q1b and D3, was a slower rise in M1 and D1a. At least 66% of sialoglycoproteins located on SDS-PAGE gel chromatograms, by radioactivity incorporated in vivo from radiolabeled N-acetylmannosamine and by (3H) sialic acid released by Neuraminidase from periodate-(3H)borohydride labeled glycoproteins, have mobilities of the cell adhesion molecules N-CAM and D-CAM. Whether the reduction of the sialoglycoproteins induced by maternal PKU is mainly in these cell adhesion molecules requires further investigation. Interference with the function of gangliosides and certain sialoglycoproteins during cerebral development may contribute to the brain dysfunction observed in the offspring of PKU mothers not on diet control during pregnancy.

Effects of maternal hyperphenylalaninemia on fetal brain development: a morphological study

We examined the effects of maternal hyperphenylalaninemia on the morphological development of the fetal and neonatal rat brain. High concentrations of phenylalanine were induced in pregnant rats from embryonic days 14 through 21 by subcutaneous injections of alpha-methylphenylalanine (mPhe) (to inhibit maternal phenylalanine hydroxylase) at a dosage of 30 mg/100 g body weight plus phenylalanine (Phe) supplementation (to raise fetal plasma phenylalanine) at a dosage of 60 mg/100 g body weight two times daily at 12-h intervals. This treatment resulted in a significant hyperphenylalaninemia compared with vehicle-injected, pair-fed control rats. At embryonic day 21, mPhe/Phe-treated embryos displayed a reduced thickness of the cortical plate and marginal zone, a decrease in the size of postmitotic neurons, and an increase in the packing density of cells in the cortical plate. There was an increase in the number of pyknotic cells (cell death) and in the reactive microglia in the mPhe/Phe-treated group. During the postnatal period the differences between mPhe/Phe-treated and control rats became fewer and by postnatal day 7 the morphology of the mPhe/Phe-exposed brains was similar to the controls. These morphologic data, in conjunction with our previous biochemical finding of reduced cerebral DNA, RNA, and protein contents of mPhe/Phe-treated rats, indicate that the induced hyperphenylalaninemia caused a significant delay in the development of the cerebral cortex which was able to undergo recovery during the postnatal period.