Changes of cytosol glucocorticoid receptor and renal Na(+)-K(+)-ATPase activity after swimming training in rat.
OBJECTIVE
The aim of this study was to determine whether the down-regulation of glucocorticoid receptor (GR) by physical changes in plasma glucocorticoid hormones (GCs) is accompanied by changes in the responsiveness of target cells to GCs in rats.


METHODS
Normal male Sprague-Dawley rats were left to swim for 60 min. At 15 min and at 3, 12, 24 h after swimming training, groups of rats were sacrificed.


RESULTS
The results show that exposure of rats to a 60-min swimming stress provokes corticosterone secretion, which results in a rapid depletion of GR from renal cytosol and the subsequent induction of the renal Na(+)-K(+)-ATPase. By employing RU38486 and Trilostane before swimming training, both the effects of GCs on regulating GR binding activity and related changes in GR binding capacity to Na(+)-K(+)-ATPase activity are also investigated. RU38486 was shown to reduce GR by about 80% and the inducing effort of GCs on Na(+)-K(+)-ATPase was prevented by pretreatment of RU38486 and Trilostane.


CONCLUSIONS
These data suggest that physiological fluctuations in endogenous hormone secretion are sufficient to result not only in substantial cytosol GR down-regulation, but in a coordinate physiological response.
Peijie
B
B
Department of Sports Medicine, Shanghai University of Sport, Shanghai, China. chengpjk@online.sh.cn
Zicai
D
D
Tian
W
W
D000818:Animals; D003600:Cytosol / Q000378:metabolism; D013196:Dihydrotestosterone / Q000031:analogs & derivatives / Q000494:pharmacology; D015536:Down-Regulation; D007668:Kidney / Q000201:enzymology*; D008297:Male; D015735:Mifepristone / Q000494:pharmacology; D010805:Physical Conditioning, Animal / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000378:metabolism*; D013550:Swimming / Q000502:physiology*
D011965:Receptors, Glucocorticoid; D013196:Dihydrotestosterone; D015735:Mifepristone; D000254:Sodium-Potassium-Exchanging ATPase; C009954:trilostane