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A developmental switch affecting growth of fatty rats
G E Truett1, J A Walker, R B Harris
1Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA. truettge@pbrc.edu
Summary
Fatty (fa/fa) rats show a developmental switch around 22 days of age. This triggers hyperphagia and rapid growth, leading to obesity.
Area of Science:
- Genetics
- Developmental Biology
- Physiology
Background:
- Fatty (fa/fa) rats accumulate adipose tissue early but appear obese later.
- Understanding the onset of obesity in these rats is crucial for metabolic research.
Purpose of the Study:
- To analyze the effects of the fa genotype on pup growth and physiological changes through 4 weeks of age.
- To identify the developmental timing of significant growth and metabolic alterations in fatty rats.
Main Methods:
- Studied fatty (fa/fa) rat pups housed with dams up to 4 weeks.
- Analyzed daily gain, stomach contents, liver weight, and plasma insulin.
- Investigated effects of litter size reduction on growth patterns.
Main Results:
- Fa genotype effects on daily gain were not significant until 23 days of age.
- A significant genotype by age interaction was observed for growth and physiological markers starting at 23 days.
- Litter size reduction did not alter the timing of these genotype effects.
Conclusions:
- A developmental switch around 22 days of age triggers hyperphagia and accelerated growth in fatty rats.
- This switch occurs independently of environmental changes like pup separation.
- The findings highlight a critical developmental window for the onset of obesity in fa/fa rats.