Rat study links smoking while pregnant to youngster's diabetes, obesity.

Feb 09, 2009

Somm, E, VM Schwitzgebel, DM Vauthay, EJ Camm, CY Chen, JP Giacobino, SV Sizonenko, ML Aubert and PS Hüppi. 2008. Prenatal nicotine exposure alters early pancreatic islet and adipose tissue development with consequences on the control of body weight and glucose metabolism later in life. Endocrinology 12:6289-6299.

Synopsis by Heather Hamlin

Results of a study that exposed pregnant rats to nicotine levels similar to those found in the blood of women who smoke has isolated how the drug alters genes that govern fat and insulin in the offspring. The permanent changes can lead to life-threatening diseases as the animals age.

This is the first study to convincingly show that mothers who smoke, or use nicotine replacement during pregnancy, could be increasing their children’s chances of developing diabetes and obesity later in life.

Human studies have found an association between prebirth nicotine exposure and both diabetes and obesity. Despite the warnings, 20-30 percent of women smokers continue the habit during their pregnancy.

Obesity and diabetes are both rising at alarming rates in the United States and other developed countries. Many researchers believe the rapid increases cannot be explained by hereditary genetics alone and think environmental exposures -- such as nicotine -- are also at play.

The collaborative team of researchers from the US and Switzerland found key changes to certain cells' gene expression that 1) controls how fat forms and 2) guides the making of healthy pancreas cells. These cell gene expression patterns are set during development in the womb.

The authors saw increased actions in genes responsible for making fat. When the mother rats were given nicotine during pregnancy, the infant rats gained more weight than those from “non-smoking” moms. Although larger infants seem healthier, the increased weight was due to excess fat. The exposed baby rats didn’t eat more, they were just more efficient at making fat than the unexposed young.

Yet, the genes that make pancreatic cells had decreased expression. The exposed pups had abnormal insulin-producing cells. One of the affected cell types is directly involved in the development of diabetes. Diabetes results when insulin is not regulated properly.

Pregnant rats were dosed with nicotine from day 4 of gestation to expose developing pups. Pancreas and fat tissue were examined in male pups before weaning. After weaning, food, fat and insulin measurements were compared between the treated and non-treated rats.