[The effects of pregnancy malnutrition on the development of insulin resistance in rat offspring]

Abstract

Objective: To investigate the effects of pregnancy malnutrition on the occurrence of insulin resistance (IR) in rat offspring during adult stage and to find out the relationship between TNF-alpha and IR; and to find out a reasonable early nutritional intervention measure for the prevention of IR, through giving different diets to offspring.

Methods: An IUGR model was built by maternal nutrition restriction. 80 newborn IUGR female pups were randomly divided into 4 groups, the mother rats were given the following diet respectively for 3 weeks after delivery, pups were fed by mother milk: (1) The IUGR (intrauterine growth retardation) rat model was used and the animals were divided into: IUGR control group (group S/N) fed with normal diet, (2) IUGR high-caloric diet group (group A), (3) IUGR high-protein and high-caloric diet group (group B) and (4) IUGR high-protein isocaloric diet group (group C). Each group had 20 pups and another 20 normal female pups were fed with normal diet as the normal control group (group C/N). All pups were weaned at the 4th week of age and fed with normal diet till the end of the experiment. At the 12th week (adulthood) and 48th week (senility) of life, body weight and length, the fasting blood glucose, insulin concentration, TNF-alpha of adipose tissue and body weight were measured. Body mass index (BMI), ISI (insulin sensitive index), IRI (insulin resistant index) and HBCI (beta cell insulin excretion index) and their correlation to TNF-alpha were calculated.

Results: At 12th week and 48th week of life, the insulin sensitivity of IUGR model group was significantly lower than group C/N, although there was no significant difference of body weight between these two groups. TNF-alpha was negatively correlated with ISI, positively correlated with IRI and no relation to HBCI. Group A and B was fatter and developed more severe IR. There were no significant differences in ISI, IRI, HBCI and TNF-alpha between group C and group C/N.

Conclusions: IUGR offspring of pregnancy malnutrition mother rats showed IR at the age of 12th week. TNF-alpha was closely related to the occurrence of IR in IUGR pups. IUGR pups fed with high caloric diet or high protein and caloric diet at the early postnatal period amplified the metabolic abnormality. The high protein isocaloric diet is effective early nutritional intervention measure for the prevention of occurrence of IR at adulthood.