Rats exposed to alcohol while still in the womb learn to like the substance and are more drawn to it as young rats, a new study shows.
The observation may help explain why teens with prior foetal exposure to drinking may be more likely to abuse the substance, researchers say.
"Exposure to something mom ate during gestation will alter its response," explained Steven Youngentob, a professor of neuroscience and physiology at State University of New York (SUNY) and member of the SUNY Upstate Developmental Exposure Alcohol Research Centre in Syracuse.
Youngentob is the lead author of two studies detailing these findings in the December issue of Behavioural Neuroscience.
Effects of alcohol on foetus
Even more than family history, foetal exposure to alcohol will predict if a person abuses alcohol later in life. And, the earlier that first experience, the higher the probability the person will have problems with this substance into adulthood, experts say.
Full-blown foetal alcohol syndrome involves profound mental retardation as well as cranial facial defects. But there are also more subtle effects of being exposed to alcohol in utero.
The senses are among earliest systems to develop and seem to allow the developing foetus to "learn" from the mother what is okay to eat and drink by virtue of what mom ingests during pregnancy, Youngentob explained.
"All that information gets transmitted to the foetus during gestation or the infant during lactation," he said. "It turns out that this adaptive mechanism is to the advantage of the organism and probably works for humans as well."
Unless it involves a substance of abuse, he added.
How the study was done
The new studies tested the hypothesis that exposure to alcohol while in the uterus resulted in an altered sensory response to the substance that then affected later behaviour.
"The hypothesis was that there are these neuroadaptive changes that essentially make the ethanol (alcohol) smell and taste better to the animal. So, the animal, because of the foetal exposure, has 'learned' that ethanol is something that's good to eat," Youngentob said.
For the first study, rats that had been exposed to alcohol in the womb via maternal consumption were more likely to choose alcohol versus a non-alcoholic substance as young rats, but not as adults.
The second study followed a similar protocol: Rats were exposed to alcohol while still in the uterus.
Compared to rats whose mothers just ate chow, the prenatal exposed rats sniffed alcohol more. They also had an altered odour response in their nasal passages.
'It's all about learning'
"We know that the foetus has smell sensations developing in utero, and this is almost a need for survival, because you see when animals are born, they immediately know where to gravitate for maternal milk. The same thing happens when you place a baby on the mother's chest, he will recognise where the breast is just by smell," noted Dr Raul Artal, professor and chair of the department of obstetrics, gynaecology and women's health at St. Louis University.
"Learning different smells in utero and becoming familiar may be something that has a role in developing smell and taste for alcohol. This is almost a primitive type of response. It has nothing to do with intelligence. It's just part of life preservation."
In both cases, if the young rat had no more experience with alcohol by adulthood, the alcohol lost its attraction.
"The good news is that in the absence of a substance being biologically relevant - that is, not being exposed to it - then the animal becomes biologically neutral again," Youngentob said.
Teens should be kept away from alcohol
"If the animals only get that foetal exposure, and you test them as adults, it's gone in terms of neurophysiological response."
But, if humans get adolescent exposure to alcohol, it can perpetuate the cycle, he said.
Youngentob and his colleagues are testing whether adolescent exposure to alcohol perpetuates the cycle in humans.
The clear message: Don't drink when pregnant, and keep alcohol away from teenagers, the researcher said. – (HealthDay News)
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