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Hyperthyroidism affects lipid metabolism in lactating and suckling rats
S M Varas1, G A Jahn, M S Giménez
1Department of Biochemistry and Biological Sciences, Faculty of Chemistry, Biochemistry, and Pharmacy, National University of San Luis, Argentina.
Lipids
|October 11, 2001
Summary
Hyperthyroidism in mothers alters maternal liver and mammary lipid metabolism, impacting infant growth. This study reveals decreased lipid synthesis in mammary glands despite increased liver synthesis, contributing to reduced pup growth rates.
Area of Science:
- Endocrinology
- Metabolic Research
- Reproductive Biology
Background:
- Hyperthyroidism (HT) affects 2% of pregnant women, with postpartum symptom exacerbation.
- Maternal thyroid hormone levels impact fetal and infant development.
- Lactation involves significant maternal metabolic adaptations, particularly in lipid metabolism.
Purpose of the Study:
- To investigate the effects of maternal hyperthyroidism on lipid metabolism in mammary glands and livers during lactation.
- To assess the impact of these metabolic changes on pup growth and thyroid hormone status.
Main Methods:
- Pregnant rats were treated with thyroxine to induce hyperthyroidism or vehicle.
- Maternal liver and mammary gland tissues, as well as pup tissues, were collected on lactation days 7, 14, and 21.
- Measurements included lipid concentrations (cholesterol, triglycerides), lipid synthesis rates (using [3H]H2O incorporation), and key enzyme activities (fatty acid synthase, acetyl CoA carboxylase).
- Circulating thyroid hormone levels in mothers and pups were also measured.
Main Results:
- Hyperthyroid mothers exhibited elevated circulating thyroid hormones.
- Maternal liver showed decreased cholesterol and triglyceride concentrations but increased lipid synthesis rates at day 14.
- Mammary glands displayed reduced triglyceride and cholesterol concentrations with decreased lipid synthesis at days 7 and 21.
- Pups of hyperthyroid mothers had reduced growth rates and altered thyroid hormone levels.
Conclusions:
- Maternal hyperthyroidism significantly alters maternal lipid metabolism in both the liver and mammary glands.
- Despite increased liver lipid synthesis, overall lipid concentrations decrease, potentially due to increased demand or altered regulation.
- These maternal metabolic disruptions, coupled with mild pup hyperthyroidism, contribute to impaired pup growth during lactation.