Upregulation Effect of Ginsenosides on Glucocorticoid Receptor in Rat Liver

We have demonstrated earlier that ginsenosides (GSS) could partially reverse the dexamethasone (Dex)-induced downregulation of glucocorticoid receptor (GR) and enhance Dex-induced transcription of GR reporter gene in HL 7702 cells, but whether it can play a similar role in vivo has not been studied. Male Sprague-Dawley rats were pretreated with saline (1 ml.d(-1))or GSS (50 mg kg(-1).d(-1)) for 5 days, and then subjected to GR downregulation induced by polyvinyl alcohol containing hydrocortisone (F-PVA). The rats were killed by decapitation to determine liver GR and plasma corticosterone levels. Pretreatment with GSS resulted in upregulation of GR with respect to binding capacity, cytoplasmic protein expression, and mRNA levels, but did not produce significant effects on GR binding affinity and serum corticosterone levels. Pretreatment with GSS also led to increase in GR translocation and TAT mRNA levels. Data obtained in the present study indicate that GSS may upregulate GR levels in vivo and enhance glucocorticoid efficiency.