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[Low-affinity binding sites of glucocorticoid]
1Department of Pathophysiology, Second Military Medical University, Shanghai, China.
Zhongguo Yao Li Xue Bao = Acta Pharmacologica Sinica
|July 1, 1991
Summary
Low-affinity glucocorticoid binding sites (LAGS) in rat tissues may mediate glucocorticoid drug activity. These sites, identified in liver, brain, and thymus cells, bind steroids and are blocked by mifepristone.
Area of Science:
- Endocrinology
- Molecular Pharmacology
- Cell Biology
Context:
- Glucocorticoids are critical hormones with diverse physiological roles.
- Understanding glucocorticoid receptor binding is key to drug development.
- Low-affinity binding sites (LAGS) have been proposed but poorly characterized.
Purpose:
- To investigate the presence and characteristics of low-affinity glucocorticoid binding sites (LAGS) in rat tissues.
- To determine the role of LAGS in mediating glucocorticoid pharmacological activity.
Summary:
- Low-affinity glucocorticoid binding sites (LAGS) with steroid specificity were identified in rat hepatic cytosol, cerebral cytosol, and thymocytes.
- Scatchard, pseudo-scatchard, and competitive analyses estimated the dissociation constant (Kd) of LAGS at 1-10 μmol/L.
- Dexamethasone binding to LAGS correlated with inhibition of [3H]UdR incorporation in rat thymocytes, and this effect was blocked by mifepristone (RU-486), a glucocorticoid antagonist.
Impact:
- These findings suggest that LAGS may play a significant role in mediating the pharmacological effects of glucocorticoids.
- This research provides a foundation for exploring LAGS as potential therapeutic targets.
- Understanding LAGS could lead to the development of more selective glucocorticoid-based therapies.