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Impaired TSH secretion during sustained hyperglucagonemia in anesthetized dogs
1VA Medical Center, Des Moines, Iowa 50310, Iowa 52242, and School of Medicine, University of Arizona, Tucson, Arizona 85724, USA.
Thyroid : Official Journal of the American Thyroid Association
|October 1, 1995
Summary
Sustained hyperglucagonemia significantly reduces thyroid-stimulating hormone (TSH) secretion and blunts the TSH response to thyrotropin-releasing hormone (TRH). This finding mimics TSH patterns observed in nonthyroidal illnesses.
Area of Science:
- Endocrinology
- Thyroid Physiology
- Hormonal Regulation
Background:
- Hyperglucagonemia is implicated in thyroid hormone alterations during nonthyroidal illnesses.
- Thyroid-stimulating hormone (TSH) secretion is frequently altered in nonthyroidal illnesses.
Purpose of the Study:
- To investigate the impact of sustained hyperglucagonemia on TSH secretion patterns.
- To assess the influence of hyperglucagonemia on the hypothalamic-pituitary-thyrotroph axis.
Main Methods:
- Sustained hyperglucagonemia was induced in 5 anesthetized dogs using intravenous glucagon.
- Serum TSH concentrations were measured before and after thyrotropin-releasing hormone (TRH) administration.
- A control study using normal saline was performed for comparison in a randomized sequence.
Main Results:
- Basal TSH levels did not differ significantly between hyperglucagonemia and control conditions.
- Serum TSH significantly declined during sustained hyperglucagonemia before TRH administration.
- TSH response to intravenous TRH was significantly blunted during glucagon infusion.
Conclusions:
- Sustained hyperglucagonemia inhibits basal TSH secretion.
- Hyperglucagonemia significantly reduces the TSH response to TRH administration.
- This observed TSH secretory pattern resembles that seen in many nonthyroidal illnesses.
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