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Fetal alcohol exposure and temporal vulnerability: effects of binge-like alcohol exposure on the developing rat
D J Livy1, E Kathryn Miller, Susan E Maier
1Division of Anatomy, University of Alberta, T6G 2H7, Edmonton, AB, Canada.
Insights
Alcohol exposure during the third trimester-equivalent in rats significantly impacts fetal alcohol syndrome (FAS) by reducing hippocampal cell size and number, potentially causing learning and memory deficits.
Area of Science:
- Neuroscience
- Developmental Biology
- Toxicology
Background:
- Fetal alcohol syndrome (FAS) is linked to cognitive deficits, particularly in learning and memory.
- The hippocampus is a brain region crucial for learning and memory, and its structure may be affected by prenatal alcohol exposure.
Purpose of the Study:
- To investigate the effects of alcohol exposure during different developmental periods on hippocampal cell structure in a rat model.
- To determine if specific regions of the hippocampus (CA1, CA3, dentate gyrus) are differentially vulnerable to alcohol during development.
Main Methods:
- Rat pups were exposed to alcohol during various gestational and early postnatal periods, mimicking human trimester equivalents.
- Control groups received nutritional or no treatment.
- Hippocampal tissue was analyzed on postnatal day 10 to assess cell volume, density, and number in CA1, CA3, and the dentate gyrus.
Main Results:
- Alcohol exposure during the third trimester-equivalent (rat) led to reduced CA1 volume, pyramidal cell density, and number.
- CA3 volume was decreased across all exposure periods, but cell density and number were only affected in the third trimester-equivalent.
- Dentate gyrus volume was unaffected, but granule cell density and number were reduced with third trimester-equivalent exposure.
Conclusions:
- The third trimester-equivalent in rats is a critical developmental window for hippocampal susceptibility to alcohol.
- Alcohol-induced damage to the hippocampus during this period may underlie the learning and memory impairments observed in fetal alcohol syndrome.
- These findings highlight the neurodevelopmental risks associated with alcohol consumption during pregnancy.
Abstract:
Children with fetal alcohol syndrome (FAS) display altered performance in tasks of learning and memory, behaviours thought to be associated with the hippocampus. Altered hippocampal structure has been reported in some FAS children; therefore, a rat model system was used to determine whether the size and numbers of pyramidal cells in regions CA1 and CA3 of the hippocampal formation and granule cells in the dentate gyrus were altered by alcohol exposure during different periods of development. Rat pups were exposed to alcohol in utero during the second trimester-equivalent (E10-20), the first two trimesters-equivalent (E1-20), during the time of hippocampal pyramidal cell neurogenesis (E16-20), part of the third trimester-equivalent (P4-9), and all three trimesters-equivalent (E1-20+P4-9). Control animals (nutritional and untreated) were reared for all treatment conditions. All pups were perfused on P10. CA1 volume, pyramidal cell density, and number were reduced in pups treated with alcohol during the third trimester-equivalent, whether unique or as exposure during all three trimesters-equivalent. CA3 volume was reduced in alcohol-treated animals across all gestational ages; however, pyramidal cell density and number in this region were only reduced in animals treated with alcohol during the third trimester-equivalent. Volume of the dentate gyrus did not appear to be affected by alcohol treatment. Granule cell density and number in this region were reduced in animals treated with alcohol during the third trimester-equivalent. The third trimester-equivalent in the rat appears to be a developmental period during which the hippocampus is particularly susceptible to the effects of alcohol consumption. The resulting damage to the hippocampus may contribute to the behavioural deficits related to learning and memory noted in children with FAS.