Zinc supplementation in ethanol-treated pregnant rats increases the metabolic activity in the fetal hippocampus

Prenatal zinc treatment at the time of acute ethanol exposure limits spatial memory impairments in mouse offspring

Zinc (Zn) treatment given together with acute ethanol in early pregnancy has previously been demonstrated to protect against physical birth abnormalities in mice. The current study examined whether this Zn treatment (s.c. injection) can also prevent the more subtle cognitive impairments caused by ethanol exposure in early pregnancy. Pregnant C57BL/6J dams were injected with saline (0.85% wt/vol NaCl) or 25% ethanol (0.015 mL/g body weight) intraperitoneally at 0 and 4 h on gestational d (GD) 8. ZnSO4 (2.5 microg Zn/g at 0 h) treatment was administered by s.c. injection immediately following ethanol treatment. Offspring were randomly selected from litters for each of the three treatment groups and were tested at 55 and 70 d of age using a cross-maze water escape task for spatial learning and memory impairments consecutively. No differences were observed between treatments for the spatial learning task. However, young adult mice exposed to ethanol in utero demonstrated impaired spatial memory, with a decrease in correct trials and increased escape latency and incorrect entry measurements, compared with saline-treated controls. In comparison, offspring given s.c. Zn treatment at the time of ethanol exposure were not cognitively impaired, performing at the same level as control mice in the cross-maze escape task. These findings indicate that critically timed Zn administration can limit spatial memory impairments caused by ethanol exposure in early pregnancy.

Effects of prenatal alcohol exposure on the hippocampus: spatial behavior, electrophysiology, and neuroanatomy

Prenatal exposure to alcohol can result in fetal alcohol syndrome (FAS), characterized by growth retardation, facial dysmorphologies, and a host of neurobehavioral impairments. Neurobehavioral effects in FAS, and in alcohol-related neurodevelopmental disorder, include poor learning and memory, attentional deficits, and motor dysfunction. Many of these behavioral deficits can be modeled in rodents. This paper reviews the literature suggesting that many fetal alcohol effects result, at least in part, from teratogenic effects of alcohol on the hippocampus. Neurobehavioral studies show that animals exposed prenatally to alcohol are impaired in many of the same spatial learning and memory tasks sensitive to hippocampal damage, including T-mazes, the Morris water maze, and the radial arm maze. Direct evidence for hippocampal involvement is provided by neuroanatomical studies of the hippocampus documenting reduced numbers of neurons, lower dendritic spine density on pyramidal neurons, and decreased morphological plasticity after environmental enrichment in rats exposed prenatally to alcohol. Electrophysiological studies also demonstrate changes in synaptic activity in in vitro hippocampal brain slices isolated from prenatal alcohol-exposed animals. Considered together, these observations demonstrate that prenatal exposure to alcohol can result in abnormal hippocampal development and function. Such studies provide a better understanding of neurological deficits associated with FAS in humans, and may also contribute to the development of strategies to ameliorate the effects of prenatal alcohol exposure on behavior.

Fetal alcohol syndrome: a Japanese perspective

To estimate and prevent the effects of prenatal alcohol on the central nervous system (CNS), brain dysfunction in fetal alcohol syndrome (FAS) and fetal alcohol effects (FAE) was compared by both epidemiological and experimental studies. The FAS infants exhibited a more severe degree of CNS involvement than the FAE infants. The CNS involvement features were developmental delay and intellectual impairment in both FAS and FAE. The increased risk of low birth weight and CNS involvement were much more significant in women who were heavy drinkers or alcoholics and smoked. The beneficial effect of supplementary zinc on the fetal cerebrum of FAS or FAE rats was limited, never reaching the unexposed control level. One of the most vulnerable structures in the rat fetus exposed to ethanol in utero was the synaptic formation in the hippocampus. The consistent dysmorphogenesis of synapses during early brain development may be associated with the functional impairment of the CNS in FAS and FAE.

Maternal risk factors in fetal alcohol syndrome: provocative and permissive influences

We present an hypothesis integrating epidemiological, clinical case, and basic biomedical research to explain why only relatively few women who drink alcohol during pregnancy give birth to children with alcohol-related birth defects (ARBDs), in particular, Fetal Alcohol Syndrome (FAS). We argue that specific sociobehavioral risk factors, e.g., low socioeconomic status, are permissive for FAS in that they provide the context for increased vulnerability. We illustrate how these permissive factors are related to biological factors, e.g., decreased antioxidant status, which in conjunction with alcohol, provoke FAS/ARBDs in vulnerable fetuses. We propose an integrative heuristic model hypothesizing that these permissive and provocative factors increase the likelihood of FAS/ARBDs because they potentiate two related mechanisms of alcohol-induced teratogenesis, specifically, maternal/fetal hypoxia and free radical formation.

Fetal alcohol effects: decreased synaptic formations in the field CA3 of fetal hippocampus

The effects of prenatal ethanol exposure on the synaptic formation in the field CA3 of the hippocampus of fetal rats have been investigated on gestational day 21. Significantly decreased number of synaptic junctions was observed in the fetus showing decreasing cerebral weight either with or without decreasing body weight. The administration of 0.01% zinc with ethanol or 0.02% alpha-tocopherol acetate with ethanol during pregnancy resulted in an increased cerebral weight, but did not result in an increased synaptic formation compared to ethanol alone. This result indicates that one of the most vulnerable factors in rat fetus exposed to ethanol in utero is the synaptic formation in the hippocampus. In conclusion, ethanol exposure in utero during a period of brain development roughly equivalent to the first and second human trimesters can produce consistent dysforming effect of synapses and may be associated with the functional impairement of the central nervous system in the fetal alcohol effects.

Abnormal movements in brindled mutant mouse heterozygotes: as related to the development of their offspring--biochemical and morphological studies

As a possible preventive measure for brain dysfunction in Menkes disease, prenatal treatment by maternal administration of zinc, vitamin E and copper was examined in brindled mutant mice. During pregnancy and lactation, female heterozygous mice received 20 ppm zinc or 0.004% alpha-tocopherol acetate (vitamin E) throughout and 6 ppm copper from gestational day 13 in the drinking fluid, ad libitum. The maternal administration of zinc and vitamin E, as antioxidants, or copper resulted in decreased fetal and neonatal death of offspring, especially those of hemizygous males, as compared with the administration of water only. When offspring did not grow, maternal abnormal movements, which comprised rotatory movements of high speed with tremor and ataxia, were frequently observed. In the heterozygotes with abnormal movements, the level of lipid peroxidation in cerebrum and the concentration of copper in kidney were much higher than those in the heterozygotes with normal movement. Morphologically, in cerebellum of the heterozygotes with abnormal movements, the loss of Purkinje cells, abundance of lipofuscin granules and abnormal mitochondria or degenerative bodies of high electron density were frequently observed, as compared with heterozygotes with normal movement. These findings suggest that the development of hemizygous male mice may be influenced by both copper and oxygen radical metabolism.

Confronting cisternae in pituitary gland thyrotrophs of congenitally hypothyroid mice

Confronting cisternae were found in pituitary thyrotrophs of congenitally hypothyroid mice. These confronting cisternae rapidly reverted back to ordinary rough endoplasmic reticulum following thyroxine administration. Confronting cisternae were not observed in the thyrotrophs of euthyroid control mice. Our results strongly suggest that confronting cisternae are a peculiar form of rough endoplasmic reticulum which appears under certain conditions of enhanced cellular metabolism.

Decreased density of synaptic formation in the frontal cortex of neonatal rats exposed to ethanol in utero

We examined the developing synaptic junctions in the rat frontal cortex in cases of fetal alcohol syndrome, the objective being to determine the synapse-mental retardation relationship. On day 21 of gestation, the ultrastructural synaptic junction revealed no obvious differences between the ethanol-exposed and control rats; however, the number of synapses in ethanol-exposed rats was one third that of the controls. The possible relationship between synaptic density in the frontal cortex and mental development has to be considered.

The protective effects of vitamin E on microcephaly in rats X-irradiated in utero: DNA, lipid peroxide and confronting cisternae

Fetuses from rats given either water or 0.03% D,L-alpha-tocopherol acetate (vitamin E) as a drinking fluid and X-irradiated with 100 rad on gestational day 13 were examined on gestational day 21. Mean cerebral weight which was significantly reduced by the X-irradiation was increased by vitamin E supplementation but the level did not reach that in sham-irradiated controls. Administration of vitamin E caused an increase in DNA concentration which was significantly reduced by X-irradiation with water treatment. An increase in the mean level of lipid peroxide formation was observed in the water-treated, X-irradiated group in the sample at zero time but not in the vitamin E-treated, X-irradiated group. In the cytoplasm of fetal cerebral neurons from X-irradiated dams with vitamin E supplementation, confronting cisternae were frequently observed between two nuclear envelopes. Confronting cisternae may be considered as a repair mechanism of vitamin E against X-irradiated neuronal damage in the fetal cerebrum. This study provides evidence of the protection by vitamin E of neuronal development in X-irradiated fetuses, through its antioxidant properties, against attacks by free radicals and/or lipid peroxide.