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Developmental changes in ob gene expression and circulating leptin peptide concentrations
S U Devaskar1, C Ollesch, R A Rajakumar
1Department of Pediatrics, University of Pittsburgh, Magee-Womens Research Institute, Pennsylvania 15213-3180, USA.
Abstract:
We examined the developmental changes in murine white and brown adipose tissue leptin and circulating immunoreactive total leptin concentrations. The approximately 4.4 kb leptin mRNA levels were higher at 2 and 7d postnatal ages, but declined to adult levels by the 14d stage and remained so until 160d. Paralleling the mRNA concentrations, leptin peptide levels also were higher at 2d, 7d, and 14d, declining to adult values by the 21d weaning stage. No difference in mRNA levels was observed between brown-enriched and white adipose tissue. No sexual dimorphism was observed in the leptin mRNA or peptide levels between 14 and 160d; however, at 2 and 7d, while no sex related differences were observed in the peptide levels, adipose mRNA concentrations were mildly higher in males than in the females. We conclude that leptin mRNA and peptide levels are higher during consumption of a high fat milk diet. High levels of leptin with increasing food intake and body weight gain signify hypothalamic leptin receptor resistance during the immediate postnatal period.
Insights
Leptin mRNA and peptide levels are elevated in early postnatal mice, particularly during high-fat milk consumption. This suggests temporary hypothalamic leptin receptor resistance in newborns.
Area of Science:
- Endocrinology
- Developmental Biology
- Metabolism
Background:
- Leptin regulates energy balance and adiposity.
- Understanding leptin's developmental trajectory is crucial for metabolic health.
- Adipose tissue is a primary source of leptin.
Purpose of the Study:
- To investigate developmental changes in leptin mRNA and peptide levels in murine adipose tissue.
- To compare leptin expression between white and brown adipose tissue.
- To examine potential sexual dimorphism in leptin levels during postnatal development.
Main Methods:
- Quantification of leptin mRNA using approximately 4.4 kb transcript levels.
- Measurement of circulating immunoreactive total leptin peptide concentrations.
- Analysis of adipose tissue from different postnatal ages (2d to 160d) and sexes.
Main Results:
- Leptin mRNA and peptide levels were significantly higher in early postnatal stages (2-14d) compared to adult levels.
- No significant differences in mRNA levels were found between brown and white adipose tissue.
- Mildly higher mRNA levels in males were observed at 2 and 7 days, but no sexual dimorphism in peptide levels.
- Elevated leptin levels correlated with high-fat milk diet and increased body weight gain.
Conclusions:
- Leptin expression is developmentally regulated, peaking in the early postnatal period.
- High postnatal leptin levels during high-fat feeding may indicate transient hypothalamic leptin receptor resistance.
- These findings contribute to understanding early-life metabolic programming and leptin signaling.