Effect of Early Nutrition on Adipose Cellularity and Pancreatic Insulin Release in the Zucker Rat

Abstract
Preweaning nutritional manipulation in the Zucker rat interacts with genotype to influence growth and adipose tissue morphology, but not pancreatic insulin release. Zucker obese (fafa) and nonobese (Fafa) male rats were over- or underfed prior to weaning by placement in large or small litters, respectively. During the first 30 days of life the nutritional effect and not the genotype was the predominant influence on the animals' growth. By 12 weeks of age, genotypic differences became the major determinant of body weight. While early overfeeding significantly increased adipocyte number in both obese and nonobese rats, early underfeeding reduced adipocyte number only in the nonobese. The release of immunoreactive insulin (IRI) from isolated pancreatic islets was a function of the animals' genotype and was uninfluenced by the early nutritional treatment. Obese rats release three to four times as much IRI as do their nonobese controls.