We already know that pregnant mothers who drink alcohol risk harming their baby's development. What we do not know is how much, if any, alcohol is acceptable during pregnancy. Nor do we know, relative to brain development, exactly how toxic alcohol may be at different stages. But now, scientists may be one step closer to understanding how alcohol hampers the brain development of exposed fetuses during the third trimester.
"Alcohol is a 'dirty drug' as it affects a variety of systems in the brain," said James R. West, Professor and Head of Anatomy and Neuroscience at the Texas A&M University Health Science Center. "Alcohol does different things at different times in different parts of the brain. During the third trimester, for example, alcohol kills some kinds of brain cells, but earlier in development, alcohol interferes with cell division." Alcohol's itinerant nature makes it a challenge to track whereas a drug like cocaine, said West, is much easier to study because it specifically affects the absorption of a neurotransmitter called dopamine.
Researchers discovered that high levels of alcohol during late fetal development kill an important group of neurons called Purkinje cells, which act to filter and synthesize information leaving the cerebellum for other brain regions. As reported in the October issue of Alcoholism: Clinical & Experimental Research, Purkinje cells need a trophic (growth-enhancing) factor called Glial Derived Neurotrophic Factor (GDNF) to survive. GDNF is one of the key growth factors necessary for Purkinje cell survival. Alcohol deprives Purkinje cells of GDNF, thereby depriving them of a means of survival.
West and his colleagues used rats to model alcohol effects on fetal brain
development. Although human gestation lasts approximately nine months, compared
to 22 days for a rat, West noted that all mammals pass through the same stages
of brain development despite the different timing of those stages. In other
Contact: James R. West, Ph.D.
Alcoholism: Clinical & Experimental Research