Ginsenoside Rb1 Protects the Brain from Damage Induced by Epileptic Seizure via Nrf2/ARE Signaling.

BACKGROUND/AIMS: Ginsenoside Rb1 (Rb1) has been reported to have varieties of neuroprotective effects. This study aimed to evaluate the effects of Rb1 on pentylenetetrazol (PTZ)-induced rat brain injury and Mg2+ free-induced neuron injury and analyzed the detailed molecular mechanisms in vivo and in vitro.

METHODS: Seizure duration and latency were measured in epilepsy kindled rat. The cognitive impairment was assessed by Morris water maze (MWM) test. Oxidative stress parameters, malondialdehyde (MDA) and glutathione (GSH) were measured by the 2-thiobarbituric acid methods and the DTNB-GSSG reductase recycling methods. Neuronal damage was assessed by hematoxylin and eosin (H&E) and Nissl staining. Neuronal apoptosis was measured by Annexin V-FITC and propidium iodide (PI) staining. Immunohistochemistry and immunofluorescence staining were performed to evaluate Nrf2 and HO-1 expressions. Expression of Nrf2, HO-1, Bcl-2, iNOS and LC3 were evaluated by western blot.

RESULTS: The PTZ-injured rats presented longer seizure duration and shorter seizure latency. Rb1 ameliorated these effects, as well as the cognitive deficits caused by PTZ exposure. Besides, Rb1 dose-dependently increased GSH levels, decreased MDA levels and alleviated neuronal damage in PTZ-treated rats. In vitro, Rb1 increased cell viability and decreased neuronal apoptosis in a dose-dependent manner under Mg2+ free condition. Moreover, in vivo and in vitro, Rb1 enhanced both the Nrf2 and HO-1 expressions. Furthermore, upregulation of the expression of Bcl-2 and downregulation of the expression of iNOS and LC3 were observed. However, knockdown of Nrf2 adversely affected the protective effects of Rb1 in epileptic hippocampal neurons.

CONCLUSION: Rb1 conferred neuroprotective effects against PTZ-induced brain damage and Mg2+ free-induced neuron injury by activating Nrf2/ARE signaling.