To test the theory that obesity in adulthood may be subject to programming during fetal development, the researchers developed an overfeeding model which was used in rats. The model allowed the investigators to replicate many of the metabolic and hormonal features of overweight human individuals. They were also able to exclude parental genetic influences, match gestational weight gain, limit the exposure of maternal obesity in utero, and control lactation efficiency, all of which can be difficult confounding variables in studies with human subjects.
Summary of Methodology
Virgin female rats were fed liquid diets via enteral nutrition at one of two caloric levels: (1) the caloric level recommended by the National Research Council (187 kcal/kg3/4/day) or (2) a level of 15 percent overfeeding (220 kcal/kg3/4/day). In the preliminary experiments, the rats consuming the normal caloric intake had weight gains similar to controls while those being fed the obesegenic diet had become substantially overweight. Body weights were monitored three times a week and body composition was analyzed non-invasively on a regular basis.
To examine the long-term gestational effects of maternal obesity on the offspring, lean (n=7) and obese (n=15) rats were allowed to mate with normal (lean) male rats for a period of one week. Following mating, all female rats (lean and obese) received respective diets at 15 percent excess calories per day in order to ensure adequate caloric intake for pregnancy. Maternal body weights were monitored three times a week and all rats gave birth naturally. Offspring born to lean or obese rats were raised by surrogates who were fed regular rodent diets to ascertain the pups' obesity exposure was limited only during gestation.
The male offspring from each group
|Contact: Donna Krupa|
American Physiological Society