Withdrawal from Chronic Ginsenoside Rb1 Treatment Alters GABAA Receptor mRNA Levels of Cultured Rat Hippocampal Neurons

Ginsenoside, one of major active ingredients of Panax ginseng, is involved in regulating synaptic transmission and has beneficial effects on protecting neuron. It was in the current study investigated the effects of withdrawal from chronic treatment of ginsenoside Rb1 and DZ on gamma-aminobutyric acid receptor (GABAR) subunits gene expression on hippocampal neurons. Exposure of cultured rat hippocampal neurons to 10 muM ginsenoside Rb1 for 5 days reduced the amounts of alpha1, gamma2, and beta2 subunit mRNAs, whereas Rbl withdrawal was associated with a persistent reduction in gamma2, and beta2 subunit mRNAs and an increase in alpha5 mRNAs. Treatment with 10 muM Diazepam (DZ) for 5 days reduced the amount of al subunit mRNA, whereas DZ withdrawal did not significantly affect the abundance of all the GABA_A subunits. The data suggest that chronic and withdrawal ginsenoside Rb1 treatment of rat hippocampal neurons in culture causes alterations in the gene expression of GABA_A receptors and ginsenoside Rb1 might have a different mechanism of action and unique receptor binding sites from that of the DZ.