Prenatal Nicotine The Key Role in SIDS?

Babies whose moms smoke during pregnancy are five times as likely to die from sudden infant death syndrome {SIDS} than our nonsmokers infants, notes Ralph E. Fregosi of Arizona State University in Tucson.  In studies with rodents, he and Zili who have now identified a possible explanation: nicotine exposure in the home may slow or even stop the firing of respiratory nerves that trigger breaths.



Earlier studies linked nicotine to SIDS. To explore what the stimulant might be doing, the researchers implanted tiny pumps under the skin of female rats on the third day of the three-week pregnancies.  The pumps delivered either saline or nicotine-the latter, in amounts that yielded blood concentrations comparable to those in people who smoke two packs of cigarettes per day.



As each pup was born, the researchers remove the animals brainstem and its spinal cord and kept that tissue alive for three days.  The nerves continued to fire signals that would normally trigger a newborn rats diaphragm to contract, thereby initiating breaths.  Luo recorded the signals before and after administering a drug that mimics gamma aminobutyric acids and {GABA}, a natural brain chemical that keeps nerves from overfiring.



In the tissue from pups that had received saline, the drug blunted the breathing system slightly.  In the tissue from nicotine teen expose newborns, neural activity dropped by 20 to 30 percent with the drug.  In some instances, the breathing breathing signals ceased.



Fregosi and Luo then counted in the sites on brain cells where GABA would typically attached.  The brain stems from the nicotine expose pups had far more of these GABA receptors than the tissue from saline-exposed rats did.  The researchers are now studying how long the prenatal nicotine renders nurse oversensitive to GABA.