Similarities and dissimilarities of newborn and adolescent rats in the binding capacity of thymic glucocorticoid receptors.
The glucocorticoid receptor of the newborn thymus binds dexamethasone with the same specificity, as the adult ones. The best competitors of dexamethasone on the glucocorticoid receptor are dexamethasone itself and mifepristone (RU486). Estradiol can compete with dexamethasone on the glucocorticoid receptor. This is true in the case of newborn or adolescent thymus alike. Allylestrenol can slightly compete with dexamethasone on the glucocorticoid receptor in newborn, however this does not occur in adolescents. The other ligands - causing imprinting or imprinting like phenomenon earlier -- as tocopherol, menadione, retinoic acid, vitamin D(3) -- do not compete in vitro with dexamethasone on the thymic glucocorticoid receptor in newborn and adolescent animals. Possibilities of imprinting mechanism, considering the results are discussed.
Csaba
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G
Department of Genetics, Cell and Immunobiology, Semmelweis University, Budapest, Hungary. csagyor@net.sote.hu
Inczefi-Gonda
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A
D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D003907:Dexamethasone / Q000378:metabolism; D005260:Female; D008297:Male; D015735:Mifepristone / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D013950:Thymus Gland / Q000378:metabolism*
D011965:Receptors, Glucocorticoid; D015735:Mifepristone; D003907:Dexamethasone