[A quantitative study on the relationship between the specific binding of glucocorticoid receptor and glucocorticoid biopotency in rat thymocytes].
The inhibitory effect of dexamethasone (Dex) on the incorporation of [3H] Urd and specific binding of [3H] Dex with glucocorticoid receptor (GR) were measured in order to quantitatively study the relationship between these two indices in rat thymocytes. The results showed that there existed a close correlation between the two indices in the range of 10(-9)-10(-5) mol/L Dex. When thymocytes were treated with RU486 in the concentration range of 10(-10)-10(-6) mol/L, both [3H] Dex specific binding and inhibitory effect of Dex were blocked with different fractions. The specific binding was linearly related to Dex biopotency. When extrapolated 100% of specific binding corresponded to 100% of biopotency while 20% of specific binding corresponded approximately to 0% of biopotency. It is likely that GR exhibited an occupancy threshold of about 20% total receptors, with only few spare ones in rat thymocytes.
Shui
L M
LM
Department of Pathophysiology, Second Military Medical University, Shanghai.
Xu
R B
RB
D000818:Animals; D001665:Binding Sites; D001682:Biological Availability; D003907:Dexamethasone / Q000378:metabolism*; D005260:Female; D008297:Male; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000502:physiology*; D013601:T-Lymphocytes / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology
D011965:Receptors, Glucocorticoid; D003907:Dexamethasone