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Zonation, paracrine function and aldosterone secretion in the rat adrenal cortex
1Department of Biochemistry, Queen Mary & Westfield College, London, UK.
Endocrine Research
|February 1, 1995
Summary
Researchers discovered a novel way the steroid 18-hydroxydeoxycorticosterone (18-OH-DOC) is stored in rat adrenal inner zones. This precursor to aldosterone is released by trypsin, suggesting a unique cellular mechanism for hormone regulation.
Area of Science:
- Endocrinology
- Molecular Biology
- Adrenal Gland Physiology
Background:
- The adrenal cortex synthesizes crucial steroid hormones, including aldosterone.
- Cellular mechanisms for steroid precursor transport and utilization are not fully understood.
Purpose of the Study:
- To investigate the localization and storage of 11 beta-hydroxylase and aldosterone synthase in the rat adrenal gland.
- To identify and characterize 18-hydroxydeoxycorticosterone (18-OH-DOC) and its cellular handling.
Main Methods:
- In situ hybridization to determine enzyme localization.
- Immunoblotting and immunocytochemistry for steroid identification.
- Isoelectric focusing (IEF) gel electrophoresis.
- Trypsin treatment of tissue and gel preparations.
Main Results:
- 11 beta-hydroxylase is localized to inner adrenal zones, while aldosterone synthase is exclusive to the glomerulosa.
- 18-OH-DOC was identified in inner adrenocortical zone membranes.
- 18-OH-DOC was not solvent-extractable from IEF gels without prior trypsin treatment.
- Trypsin preincubation of adrenal tissue enhanced aldosterone output and depleted the trypsin-releasable 18-OH-DOC pool.
Conclusions:
- 18-OH-DOC is synthesized and stored in inner zone cells via a novel non-solvent extractable mechanism.
- This sequestered 18-OH-DOC can be mobilized for aldosterone synthesis in the glomerulosa.
- Suggests a unique pathway for steroid precursor regulation in the adrenal cortex.