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Energy expenditure and adipose tissue development in 2- to 8-day-old Zucker rats
Insights
Impaired energy expenditure in Zucker fa/fa pups is linked to early obesity development. Lower gas exchange levels correlate with increased adipocyte volume, confirming a defect preceding adipose tissue overdevelopment.
Area of Science:
- Metabolic research
- Developmental biology
- Genetics
Background:
- Obesity is a complex condition with genetic and metabolic components.
- Zucker fa/fa rats are a model for studying genetic obesity.
- Early life factors significantly influence obesity development.
Purpose of the Study:
- To investigate the relationship between energy expenditure and obesity onset in Zucker fa/fa pups.
- To determine if impaired energy expenditure precedes adipose tissue overdevelopment.
- To analyze metabolic and cellular changes in early life stages.
Main Methods:
- Measurement of gas exchange (oxygen consumption) in Zucker fa/fa and Fa/fa pups at 2, 5, and 7 days of age.
- Biopsy of inguinal adipose tissue to determine cellularity and triglyceride content at 3, 6, and 8 days.
- Comparative analysis between obese (fa/fa) and lean (Fa/fa) littermates.
Main Results:
- Gas exchange levels were significantly lower in fa/fa pups compared to Fa/fa pups at all studied ages.
- Adipose cell volume and triglyceride content were significantly higher in fa/fa pups at 5 and 7 days.
- A negative correlation was observed between oxygen consumption and adipocyte volume.
Conclusions:
- An energy expenditure defect is present in fa/fa pups before the overdevelopment of adipose tissue.
- This early metabolic defect is crucial for the onset and progression of genetic obesity.
- Findings highlight the importance of early-life energy balance in obesity development.
Abstract:
We investigated a possible relationship between impaired energy expenditure and the development of obesity in Zucker fa/fa pups in the first week of life; 19 fa/fa and 16 Fa/fa pups from four litters were studied. Gas exchanges were measured at 30 degrees C, from 17.00 to 18.00 hours, at the ages of 2, 5 and 7 days. At days 3, 6 and 8, a partial biopsy of inguinal adipose tissue was performed in the morning and used for determination of cellularity and TG content. At all ages studied, the level of gas exchange was significantly higher in Fa/fa than in fa/fa pups. At 5 and 7 days, but not at 2 days, adipose cell volume and triglyceride content were significantly higher in fa/fa than in Fa/fa pups, and a significant negative correlation was found between the level of O2 consumption and the volume of adipocytes. These results confirm the importance of the energy expenditure defect, which is present in fa/fa pups before the overdevelopment of adipose tissue, in the onset and development of this genetic obesity.