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Insulin resistance during suckling period in rats
Insights
Suckling rats exhibit insulin resistance, with impaired glucose metabolism and high hyperglycemia. Weaning to a high-carbohydrate diet resolves this insulin resistance in young rats.
Area of Science:
- Physiology
- Endocrinology
- Metabolic Research
Background:
- Glucose metabolism regulation is critical in early development.
- Understanding developmental changes in insulin sensitivity is important for metabolic health.
Purpose of the Study:
- To investigate glucose metabolism and insulin sensitivity in suckling versus weaned rats.
- To determine the impact of weaning onto a high-carbohydrate diet on insulin resistance.
Main Methods:
- Comparison of basal glucose turnover rates between suckling and weaned rats.
- Assessment of hyperglycemia and insulin response following glucose infusion.
- Application of the euglycemic-hyperinsulinemic clamp technique to evaluate insulin's effect on glucose kinetics.
Main Results:
- Suckling rats showed significantly higher hyperglycemia and impaired hepatic glucose suppression compared to weaned rats under hyperinsulinemic conditions.
- Weaned rats demonstrated a fourfold greater increase in glucose utilization, indicating improved insulin sensitivity.
- Insulin resistance was evident in suckling rats, characterized by elevated plasma insulin levels and reduced insulin-mediated glucose uptake.
Conclusions:
- Suckling rats exhibit a state of insulin resistance that is resolved after weaning onto a high-carbohydrate diet.
- Dietary composition plays a crucial role in the development and resolution of insulin sensitivity during early life stages.
- These findings highlight the dynamic nature of glucose metabolism regulation and insulin sensitivity during postnatal development.
Abstract:
Glucose metabolism was studied in 13- to 15-day-old suckling rats and 28- to 30-day-old rats weaned at 19 days on a high-carbohydrate, low-fat diet. The glucose turnover rate in the basal state was similar in suckling and weaned rats (14 mg X min-1 X kg-1). Glucose infusion (20 mg X min-1 X kg-1) produced a moderate hyperglycemia in weaned rats (150 mg/dl), whereas the suckling rats developed a high hyperglycemia (280 mg/dl), despite a large increase of plasma insulin concentration. The effect of insulin on glucose kinetics was then assessed by the euglycemic-hyperinsulinemic clamp technique. The plasma insulin levels reached were 736 +/- 87 microU/ml in the suckling and 444 +/- 34 microU/ml in the weaned rats, despite similar insulin infusion rates. Hepatic glucose production was suppressed by 90% in the weaned rats, whereas it remained at 40% of basal value in the suckling rats. The increase of glucose utilization above basal was fourfold higher in the weaned than in the suckling rats. Thus an insulin resistance state is present in the suckling rats and disappears after weaning onto a high-carbohydrate diet.