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Thyroid hormone responses to feeding in ob/ob mice
1Sansum Medical Research Foundation, Santa Barbara, California.
Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme
|October 1, 1989
Summary
Obesity in ob/ob mice is not due to low thyroid hormones. Instead, metabolic issues in these mice stem from impaired hormone deiodination and defective target tissue responses.
Area of Science:
- Endocrinology
- Metabolic Disorders
- Mouse Models
Background:
- Obesity, hypometabolism, and hypothermia in ob/ob mice may stem from reduced thyrotropin and thyroid hormones.
- Previous research suggested a link between these metabolic disturbances and thyroid hormone levels.
Purpose of the Study:
- To investigate the circulating levels of thyrotropin (TSH) and thyroid hormones (T4, T3) in obese (ob/ob) and lean mice.
- To examine the hormonal responses of obese mice to feeding and fasting conditions.
- To determine the cause of metabolic disturbances in ob/ob mice.
Main Methods:
- Measurement of TSH, total T4, and T3 concentrations in ad libitum-fed obese and lean C57BL/6 mice housed at 22°C.
- Assessment of hormonal responses to overnight food deprivation and meal ingestion.
- Comparison of hormone levels between sexes and phenotypes.
Main Results:
- Obese mice exhibited TSH levels similar to lean controls, with slightly higher total T4 and T3 concentrations.
- Hormonal responses to food deprivation and ingestion were comparable between obese and lean mice.
- Male mice generally had higher TSH, T4, and T3 levels than females, with greater responsiveness to feeding conditions.
Conclusions:
- Depressed pituitary-thyroid hormone levels do not account for the metabolic disturbances in ob/ob mice.
- Defective target tissue responses and impaired hormone deiodination are more likely causes.
- Thyroid hormone regulation and metabolism in ob/ob mice warrant further investigation.