Effects of early postnatal growth restriction and subsequent catch-up growth on body composition, insulin sensitivity, and behavior in neonatal rats
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Ming-Yu Jou1, Bo Lönnerdal, Ian J Griffin
1Department of Nutrition, University of California-Davis, Davis, California, USA.
Insights
Early postnatal growth restriction in neonatal rats impacts development. Catch-up growth improves outcomes but increases body fat, without affecting glucose levels.
Area of Science:
- Neonatology
- Developmental Biology
- Endocrinology
Background:
- Preterm infants often experience early growth issues followed by catch-up growth.
- A neonatal rat model was developed to study ex utero growth restriction and catch-up growth.
Purpose of the Study:
- To investigate the effects of early postnatal growth restriction and subsequent catch-up growth on neonatal rat development.
- To assess the impact on body composition, insulin sensitivity, and learning behavior.
Main Methods:
- Newborn rats were assigned to normal (NN) or restricted (R) litter sizes.
- Restricted pups were further divided into groups with varying catch-up (RC, RN) or continued restricted (RR) intake.
- Evaluated body weight, composition, insulin sensitivity, biochemistry, and passive avoidance learning.
Main Results:
- Restricted growth (R) significantly lowered body weight compared to normal (NN).
- Catch-up groups (RC, RN) showed improved growth and learning compared to restricted groups (RR, RN).
- Catch-up growth (RC) led to higher fat mass; insulin sensitivity remained unchanged across groups.
Conclusions:
- Early postnatal growth restriction negatively affects medium-term growth and developmental outcomes.
- Increased catch-up growth improves developmental outcomes but is linked to increased adiposity.
- Catch-up growth did not significantly impact glucose homeostasis in this model.
Background:
Early postnatal growth retardation with subsequent catch-up growth is common in preterm infants. We describe a model of ex utero (postnatal) growth retardation followed by varying degrees of catch-up growth in the neonatal rat.
Methods:
Newborn CD rat pups were randomized to litters of 10 (NN, normal then normal intake) or 16 (R, restricted intake). On day 10, R pups were further randomized to litters of 6 (RC, restricted then catch-up intake), 10 (RN, restricted then normal intake), or 16 (RR, restricted then restricted intake). Body weight, body composition, insulin sensitivity, biochemistry, and learning (passive avoidance test) were assessed.
Results:
Growth was significantly lower in the R than the NN group. Subsequently, the RC group caught up with the NN group but had higher fat mass; the RN group showed partial catch-up but body composition similar to that of the NN group. Insulin sensitivity did not differ between groups. Learning behavior was significantly better in the NN than the three R groups, and in the RC group than the RR or RN groups.
Conclusion:
Early postnatal growth retardation is associated with poorer medium-term growth and poorer developmental outcome. Increased catch-up growth is associated with improved developmental outcome but with increased body adiposity, without any significant effect on glucose homeostasis.
