Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, July 11, 1995 TAG: 9507110091
SECTION: NATIONAL/INTERNATIONAL PAGE: A-3 EDITION: METRO
SOURCE: Associated Press
DATELINE: LENGTH: Medium
Nicotine exposure in utero appears to shut down a stress reaction that normally helps newborns survive low-oxygen conditions, according to a new study using an animal model of sudden infant death syndrome.
Researchers at Duke University in Durham, N.C., exposed pregnant rats to nicotine and then placed their day-old offspring in a low-oxygen environment, similar to that of a human infant whose breath is blocked by a pillow. They found that one-third of the baby rats died for lack of the stress reaction mechanism, a hormone that governs heartbeat and blood flow in response to low oxygen, or hypoxia.
It has long been known through epidemiological studies that cigarette smoke is the strongest risk factor for SIDS, a term describing sudden unexplained death in children under 1 year of age.
Theodore Slotkin and colleagues at Duke believe their rat study could explain how smoking during pregnancy increases SIDS risk.
``We believe this is the same mechanism that operates in humans,'' said Slotkin, a professor of pharmacology, neurobiology and psychiatry. ``I just hope that this information will dissuade mothers from smoking'' and from using nicotine patches.
Slotkin's studies have shown that the stress hormones, produced by the adrenal glands, are important to the developing fetus and in the first year of life. If oxygen is low, the hormones are used to redistribute blood flow in the brain and heart, and to maintain cardiac rhythm.
But nicotine exposure in utero interferes with these special systems, Slotkin said, so that they shut down too soon. The adrenal gland connects to the brain at about one year of age, providing automatic stress responses for the rest of life.
Slotkin, who has been studying the effects of nicotine in humans for two decades, said, ``We hope that we can develop a test to predict whether this mechanism is functioning properly in newborn babies.''
Slotkin said that being able to tolerate low oxygen is especially important during the birthing process, so the same nicotine effect could explain the fact that the infants of women who smoke are more likely to die during delivery.
by CNB