title: Development of insulin-sensitivity at weaning in the rat. Role of the nutritional transition.
abstract: This study was undertaken to determine the factors involved in the development of insulin-sensitivity at weaning. Glucose kinetics were studied in suckling rats and in rats weaned on to a high-carbohydrate (HC) or a high-fat (HF) diet, in the basal state and during euglycaemic-hyperinsulinaemic-clamp studies. These studies were coupled with the 2-deoxyglucose technique, allowing a measure of glucose utilization by individual tissues. In the basal state, the glycaemia was higher in HF-weaned rats (124 +/- 4 mg/dl) than in suckling (109 +/- 1 mg/dl) and HC-weaned rats (101 +/- 3 mg/dl). Glucose turnover rates were similar in the three groups of animals (14 mg/min per kg). Nevertheless, basal metabolic glucose clearance rate was 20% lower in HF-weaned rats than in the other groups. During the euglycaemic-hyperinsulinaemic experiments, hepatic glucose production was suppressed by 90% in HC-weaned rats, whereas it remained at 40% of basal value in suckling and HF-weaned rats, indicating an insulin resistance of liver of these animals. Glucose clearance rate during the clamp was 18.3 +/- 0.9 ml/min per kg in suckling rats, whereas it was 35.3 +/- 1.2 ml/min per kg in HC-weaned rats and 27.8 +/- 1.1 ml/min per kg in HF-weaned rats, indicating an insulin resistance of glucose utilization in suckling, and to a lower extent, in HF-weaned rats. The deoxyglucose technique showed that peripheral insulin resistance was localized in muscles and white adipose tissue of suckling and HF-weaned rats. These results indicate that the switch from milk to a HC diet is an important determinant of the development of insulin-sensitivity at weaning in the rat.
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D000833:Animals, Suckling / Q000378:metabolism*; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D009132:Muscles / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014886:Weaning
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D007328:Insulin; D005947:Glucose