Upstate study links prenatal nicotine exposure to smoking preference later in life

Fetal nicotine exposure as a consequence of maternal smoking is known to have negative effects on the developing unborn child leading to, for example, retarded fetal growth, premature birth and increased mortality of newborn, as well as a variety of behavioral changes later in life. As an added consequence, children of women who smoked cigarettes and/or used other nicotine products during their pregnancies are four times as likely to become smokers themselves, starting as young as 12, and have a greater probability of adolescent abuse and adult addiction to nicotine.

Despite health care warnings, 25 percent of women who smoke continue to do so while pregnant. “Given the extent to which maternal tobacco use occurs during pregnancy,” says Upstate Medical University researcher, Steven Youngentob, PhD, “understanding why the progeny of these mothers first start using tobacco products is critical to both prevention and timely treatment.”  Youngentob’s laboratory, in Upstate’s Department of Psychiatry, studies what influences these children to have that first cigarette or similarly, that first drink in children exposed to alcohol during pregnancy.

A recent study by Upstate graduate student, Nicole Mantella, in the Youngentob lab, sheds light on the nicotine question. The study was published Dec. 17 in PLOS ONE, an international, peer-reviewed, open-access, online publication reporting on primary research from different scientific disciplines. The title of the study is Fetal Nicotine Exposure Increases Preference for Nicotine Odor in Early Postnatal and Adolescent, But Not Adult, Rats.

According to Mantella, nicotine, like other chemosensory (smell and taste) stimuli, is a substance capable of infiltrating amniotic fluid which is the liquid surrounding the developing child in the womb. The fetus is exposed to the nicotine by ingesting it, through the skin and also the maternal blood flow.

“In essence, we wanted to know if exposure to nicotine in the womb would result in a preference for nicotine odor later in life.”  This was important because a previous series of studies by the Youngentob lab, using alcohol, showed a fundamental connection between olfactory function (relating to the sense of smell) and postnatal acceptance of the substance as an outcome of fetal drug experience. More specifically, fetal experience with alcohol altered the olfactory system such that the aversive odor properties of the drug became more acceptable so as to enhance intake. “So we wanted to extend this to see if children who are exposed to nicotine in utero would be primed to have a preference for the drug later in life” said Mantella.

By means of behavioral and neurophysiologic approaches, the team examined whether fetal nicotine exposure in rats altered the response to nicotine odor in early postnatal, adolescent and adult animals.

They found that, indeed, in utero nicotine exposure yielded an instinctive behavioral responsiveness to the odor of nicotine that was prominent in the early postnatal animal.  This showed interest and attraction to the odor.  Importantly, while evident in adolescence, absent further experience with nicotine, the effect waned during adolescence, being completely ameliorated by adulthood.

The study also examined the effects of fetal nicotine at the neurobiological level. Electrophysiological activity recorded from the cells in the rat nose sensitive to odors showed a tuned response to nicotine odor in prenatally exposed animals.

According to Youngentob, the nicotine data adds to a growing body of evidence showing there are fetal experience-based smell and taste mechanisms by which a mother’s drug use (preference and intake) can be transferred to their progeny.

Caption: The laboratory of Steven Youngentob, PhD, photographed, is offering insight into why the progeny of mothers who smoke during pregnancy may be primed to have a preference for nicotine later in life.

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