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Early motor development and cerebral cortical morphology in rats exposed perinatally to alcohol
S Norton1, P Terranova, J Y Na
1Department of Pharmacology, University of Kansas Medical Center, Kansas City 66103.
Insights
Prenatal alcohol exposure in rats significantly delayed motor development, specifically reflex suspension and negative geotaxis. This correlated with a notable decrease in frontal cortex Lamina VI thickness, impacting motor integration.
Area of Science:
- Neuroscience
- Developmental Biology
- Toxicology
Background:
- Prenatal alcohol exposure is a known risk factor for developmental abnormalities.
- Early motor development and cerebral cortical morphology are sensitive indicators of neurodevelopmental impact.
Purpose of the Study:
- To investigate the effects of prenatal alcohol exposure on early motor development and frontal cortex morphology in rats.
- To correlate specific motor deficits with observed changes in cortical structure.
Main Methods:
- Rats were exposed to alcohol during pregnancy and lactation.
- Motor function was assessed using righting reflex, negative geotaxis, and reflex suspension tests.
- Cerebral cortical morphology, specifically laminar thickness, was analyzed in offspring.
Main Results:
- Alcohol-exposed offspring showed significantly delayed negative geotaxis and reflex suspension (approx. 2 days).
- A marked decrease (approx. 25%) in the thickness of frontal cortex Lamina VI was observed in alcohol-exposed offspring.
- Righting reflex showed a slight, non-significant delay.
Conclusions:
- Prenatal alcohol exposure leads to significant delays in specific motor behaviors requiring frontal integration.
- Alterations in frontal cortex Lamina VI thickness are associated with these motor deficits.
- These findings highlight the neurodevelopmental impact of alcohol on motor control and cortical development.
Abstract:
Specific tests of early motor development and cerebral cortical morphology were studied in rats born from alcohol-fed mothers, pair-fed mothers, and ad libitum controls (either liquid or pellet diets). Liquid Bio-Serv diets were used. Alcohol feeding began on day 5 of pregnancy and ended on day 10 postpartum. The weight gain of the pups after birth was drastically reduced compared with pair-fed and other control groups; however, removal of the alcohol on day 10 postpartum resulted in an upswing of the growth curve that paralleled control groups. Between days 2 and 21 (postnatal) three behavioral tests of motor function were performed. Righting reflex (time for an animal to return to all four feet after being placed on its dorsum) was slightly delayed but the delay was not significant. Negative geotaxis (time for an animal to rotate 180 degrees from a head-down position on an inclined plane), and reflex suspension (time an animal maintained its grip on a crossbar) were significantly delayed (approximately 2 days) in offspring from alcohol-fed mothers. In the frontal cortex the offspring of alcohol-treated mothers, a marked decrease (approximately 25%) in thickness of Lamina VI was found while the other Lamina (I-V) were less altered. These results indicate that the effect of alcohol on the frontal cortex is related to a significant delay in motor development of reflex suspension and negative geotaxis since both of these require frontal integration.