Objective: About 20 - 50% individuals with intrauterine growth retardation (IUGR) could not achieve catch-up growth and remain small in size till adulthood. There are few reports on the relation between intestinal development and body catch-up growth of IUGR. Studies showed that early "nutritional programming" would results in long-term effects on the body growth and organic function, and gastrointestinal development is closely related to the body development as well. The authors aimed to study the effect of early nutritional interventions on serum IGF1, IGFBP3, intestinal development and catch-up growth of pups with IUGR by using diets with different protein and caloric levels during the first four weeks of life.
Methods: An IUGR rat model was established by maternal nutrition restriction during pregnancy. Thirty-two IUGR female pups were divided randomly into 4 groups (8 pups in each group) and eight normal female pups as control. The groups and interventions were (1) Normal control group (C group); (2) IUGR control group (S group), (3) IUGR low-protein diet group (SL group); (4) IUGR high-protein diet group (SH group); (5) IUGR high-caloric group (SA group). The serum IGF1, IGFBP3, body weight, body length, and intestinal weight, length, intestinal villi height (VH), crypt depth (CD), villi absorbing area (VSA), mucous thickness (MT) were measured at the 4(th) week of life.
Results: (1) At the 4(th) week, the serum IGF1 (724.0 +/- 153.5 ng/ml), IGFBP3 (9.69 +/- 3.13 ng/ml), and VH (416.9 +/- 46.3 microm), VSA (115.9 +/- 24.0 x 10(3) microm(2)), MT (583.9 +/- 68.5 microm) in the SH group were significantly higher than those of normal control group (539.4 +/- 198.4 ng/ml, 4.77 +/- 2.98 ng/ml and 322.1 +/- 25.8 microm, 85.8 +/- 17.8 x 10(3) microm(2), 480.0 +/- 61.5 microm) and IUGR control group (P < 0.05). The intestinal weight (1.91 +/- 0.16 g) and length (80.67 +/- 9.47 cm) in the SH group was not significantly different from the normal control group (2.24 +/- 0.22 g and 74.77 +/- 9.06 cm, P > 0.05). The SH group showed the fastest catch-up growth. Their body weights (40.14 +/- 11.03 g) at the 3(rd) week and body lengths (23.61 +/- 0.49 cm) at the 4(th) week of life reached the normal ranges of the control group (44.65 +/- 5.36 g and 23.10 +/- 1.42 cm, P > 0.05). (2) The serum IGF1 (346.7 +/- 85.3 ng/ml), IGFBP3 (1.4 +/- 0.21 ng/ml), body weight (21.41 +/- 3.54 g) and body length (15.96 +/- 1.29 cm) and the most of intestinal indexes in the SL group were markedly lower than other groups at the 4(th) week of life (P < 0.05).
Conclusion: The serum IGF1 was a sensitive marker to reflect the catch-up growth and nutritional status, and IGF1 was positively correlated with the intestinal development and body growth. When given different nutritional interventions during the first four weeks of life, high protein diet is more helpful for the IUGR catch-up growth by promoting the intestinal development and the absorption of nutrition.