Study on glucocorticoid receptor of brain cytosol in rats with traumatic brain edema

The high-affinity glucocorticoid binding sites(HAGS)and the low-affinity glucocor-ticoid binding sites(LAGS)with steroid specificity were demonstrated in cerebral cytosol ofrats by using the radioligand binding assay.The equilibrium dissocation constant(Kd)of HAGSand LAGS were(2.78+0.71)×10mol/L and(2.12±1.06)×10mol/L respectively as esti-mated by Scatchard and Pseudoseatchard analysis.Glucocorticoid receptors(GR)in the trau-matized(left)hemisphere cytosol were decreased more significantly than those in both the con-trol(right)hemisphere cytosol at 6 h postinjury and normal brain tissue(P<0.05),but Kd ofGR showed no significant changes.GR of liver cytosol at 6h postinjury were more markedly de-creased than normal hepatic cytosol,but Kd of GR underwent no significant changes.These da-ta demonstrate that high-dose glucocorticoid(GC)used in the treatment of traumatic brain ede-ma might maintain target-cell reactions by increasing the production of GC receptor complexesand is most likely to be mediated by LAGS.