Abstract:

Objective To investigate the effects of lower birth weight and catch-up growth on islet function of rats. Methods An animal model of lower birth weight (birth weight lower than 2 standard deviations of the average of control) and high fat diet was established (model group), and the other animal model of normal diet after normal birth was used as control (normal group). The body weight of rats aged 3, 7, 11 and 15 weeks and the weight of epididymal fat were recorded and compared in two groups. Glucose metabolism was evaluated by oral glucose tolerance test (OGTT), and insulin sensitivity was determined by hyperinsulinaemic-euglycaemic clamp test in two groups of rats aged 15 weeks. Double-label immunofluorescence assay was adopted to observe the islet architecture of two groups of rats aged 16 weeks. Results The body weight and weight of epididymal fat of rats aged 15 weeks in model group were significantly higher than those in normal group (P<0.05). Fasting blood glucose and blood glucose of 30, 60 and 120 min after glucose loading in model group were significantly higher than those in normal group (P<0.05), the steady-state blood glucose and basal insulin in model group were significantly higher than those in normal group (P<0.05), while the glucose infusion rate in model group was significantly lower than that in normal group (P<0.05). Double-label immunofluorescence assay revealed that the islet architecture of rats in model group was disrupted, and the ratio of area of insulin to total area of islet in model group (0.59±0.09) was significantly lower than that in normal group (0.73±0.08）(P<0.05). Conclusion Rats with lower birth weight and catch-up growth have impaired glucose tolerance and insulin resistance, which may be associated with the reconstruction of islet structure and reduction of β cell mass.

Key words: birth weight, catch-up growth, islet