Ginsenoside Rb1 On Rat Hippocampal Neurons Gaba_a Receptor Subunit Expression

Ginsenosides, also called ginseng saponins, are the major pharmacologically active ingredients of ginseng, which is one of the most widely used herbal medicines worldwide. Several reports indicated that ginsenoside is involved in regulating synaptic transmission and has beneficial effects on protecting neuronal. It has been demonstrated that ginsenoside Rb and Rc exhibit a sedative effect on the central nervous system. A number of studies have documented that ginsenosides Rb1 and Rg1 play a major role in exerting effects on the central nervous system. However, the inhibitory effect of Rb1 is still elusive.Synaptic inhibition in the brain is largely a result ofγ-aminobutyricacid (GABA) signaling. The fast inhibitory actions of GABA are mediated by the activation of GABAA receptors (GABAARs) in the brain. GABAARs are also clinically relevant drug targets for anti-convulsant, anxiolytic and sedative-hypnotic agents. Hippocampus is an important component of limbic system, with abundance and concentrated neurons, it possesses relatively simple and high sequence sandwich and the neurons are independent distribution, and have an important actions of sleep, learning, memory, feeling and autonomic function. It is important to investigate whether ginsenoside Rb1 has any effects on GABAARs in Hippocampus, in order to know the inhibitory effect of ginsenoside Rb1.In our study, we treated primary cultures of rat hippocampal neurons by different concentrations of ginsenoside Rb1 for different time, in order to examine the effects of ginsenoside Rb1 on GABAA receptorα1,α3,α4,α5,γ1,γ2, andβ2 subunits. In comparison with those of the diazepam, we are interested in whether the ginsenoside Rb1 affects GABAA receptor in hippocampal neurons and whether the effects are different from that of the diazepam.When used 1μM, 10μM, 100μM ginsenoside Rb1 for the treatment of primary cultures of rat hippocampal neurons, it shows that shows that a higher concerntration of ginsenoside Rb1 induced a larger effect in GABAARs mRNA expression and the effect also showed that ginsenoside Rb1 really affects GABAA receptor in hippocampal neurons.In the levels of specific GABAA receptor subunit mRNAs in response to different time of treatment with ginsenoside Rb1 are different from that of diazepam. It seems that both ginsenoside Rb1 and diazepam act via GABARs, but each has a different mechanism of action and unique receptor binding sites.To assess whether the treatment also affected GABAAR subunit protein levels in primary cultures of rat hippocampal neurons, we performed western blot analysis forα1 subunit. The results are consistent with the results from mRNA levels.