The high-affinity glucocorticoid binding sites (HAGS) and the low-affinity glucocorticoid binding sites (LAGS) with steroid specificity were demostrated in cerebral cytosol of rats by using the radioligand binding assay. The Kd of HAGS and LAGS were (178?0.71)?l0-8mol/L and (2.12?1.06)?10-6mol/L respecitively as estimated by Scatchard and Pseudoscatchard analysis. Glucocorticoid receptors (GR) in the traumatized(left) hemisphere cytosol were decreased more significantly than those in both the control (right) hemisphere cytosol at 6h postinjury and normal brain tissue (P

The present study was undertaken by radioligand binding assay to compare the binding properties of U72099E to cytosol and synaptic plasma membrane (SPM)preparations of rat brain. The results showed that the binding of [3H]Glucocorticoids ([3H]GC) was not displaced by U72099E in cytosol but was displaced in SPM with a Ki of 32.2?1.7?mol/L-1,indicating the existence of binding sites for U72099E in plasma membrane (most probably being glucocorticoid membrane receptors, GCMR). The Ki of U72099E is close to the concentrations needed to mimic the actions of it to protect against brain injury, suggesting that GCMR may mediate the beneficial effect of U72099E.