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Ultra short-loop feedback control of thyrotropin secretion
Mark F Prummel1, Leon J S Brokken, Wilmar M Wiersinga
1Department of Endocrinology & Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. m.f.prummel@amc.uva.nl
Thyroid : Official Journal of the American Thyroid Association
|December 14, 2004
Summary
Pituitary hormones regulate themselves through short and ultra-short feedback loops, influencing secretion independently of target organs. Receptors for pituitary hormones in the pituitary and hypothalamus confirm these self-regulatory mechanisms.
Area of Science:
- Endocrinology
- Neuroendocrinology
- Molecular Biology
Background:
- Pituitary hormone secretion is traditionally viewed as regulated by long feedback from target organs.
- Emerging evidence suggests shorter feedback loops involving pituitary hormones themselves.
Purpose of the Study:
- To explore the existence and mechanisms of short and ultra-short feedback loops in pituitary hormone regulation.
- To investigate the role of pituitary hormone receptors in the hypothalamus and pituitary.
Main Methods:
- Review of historical observations and recent findings on pituitary hormone feedback.
- Demonstration of pituitary hormone receptors in the hypothalamus and adenohypophysis.
- Analysis of thyrotropin receptor (TSHR) function and autoantibodies.
Main Results:
- Pituitary hormones exert feedback control at hypothalamic (short) and pituitary (ultra-short) levels.
- Receptors for pituitary hormones are present in the hypothalamus and adenohypophysis.
- Pituitary TSHR is involved in autoantibody-mediated TSH suppression, relevant to Graves' disease.
Conclusions:
- Pituitary hormone secretion involves complex self-regulatory mechanisms beyond long feedback.
- These ultra-short and short feedback loops play a significant role in endocrine homeostasis.
- Understanding these mechanisms is crucial for interpreting conditions like Graves' disease.