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Steroid sequestration within the rat adrenal zona glomerulosa
S M Laird1, G P Vinson, B J Whitehouse
1Department of Biochemistry, St Bartholomew's Hospital Medical College, London.
The Journal of Endocrinology
|May 1, 1988
Summary
Rat adrenal zona glomerulosa stores 18-hydroxydeoxycorticosterone (18-OH-DOC) within tissue, not just secreted. This sequestration is linked to the plasma membrane, suggesting 18-OH-DOC is the primary stored steroid.
Area of Science:
- Endocrinology
- Cell Biology
- Steroid Biochemistry
Background:
- In vitro studies suggest 18-hydroxysteroids are stored in rat adrenal zona glomerulosa.
- Investigating steroid storage mechanisms is crucial for understanding adrenal function.
Purpose of the Study:
- To determine the extent and nature of steroid sequestration within the rat adrenal zona glomerulosa.
- To identify the specific steroid(s) involved and their cellular localization.
Main Methods:
- Comparing steroid content in zona glomerulosa tissue versus incubation media.
- Analyzing steroid distribution after plasma membrane enrichment via lysis.
- Density gradient centrifugation of homogenized tissue and plasma membrane preparations.
Main Results:
- 18-hydroxydeoxycorticosterone (18-OH-DOC) and 18-hydroxycorticosterone (18-OH-B) are retained in tissue against concentration gradients.
- Lysis and incubation of plasma membranes released more 18-OH-DOC, indicating metabolic conversion.
- Tissue 18-OH-DOC associates with a high-density plasma membrane component.
Conclusions:
- 18-OH-DOC is the major sequestered steroid in the rat adrenal zona glomerulosa.
- Sequestration is attributed to 18-OH-DOC's association with plasma membrane components.
- Tissue-sequestered 18-OH-DOC may serve as a precursor for aldosterone synthesis.