Ginsenoside Re protects against chronic restraint stress‐induced cognitive deficits through regulation of NLRP3 and Nrf2 pathways in mice

Exposure to chronic stress negatively affects the development of cognition, characterized by learning and memory decline. Ginsenoside Re (GRe), an active compound derived from Panax ginseng, exhibited neuroprotective activity in various neurological diseases. In this study, the protective effect of GRe on chronic restraint stress (CRS)-induced memory deficit was investigated. The mice were experienced 35 days of the CRS induction. The GRe was administered daily orally (10, 20, or 40 mg/kg) during the next 3 weeks stress session and the behavior test period. The CRS-induced memory impairment mice were subjected to behavioral tasks, such as the Y-maze, novel objects recognition, and step-through passive avoidance tests. Nissl staining was used to examine the neuron numbers. The levels of antioxidant enzymes, malondialdehyde, and proinflammatory factor were determined by kits and ELISA assays. The expressions of brain-derived neurotrophic factor (BDNF), NOD-like receptor protein 3 (NLRP3), nuclear factor erythroid-2 related factor 2 (Nrf2) and synapse-associated proteins (synaptophysin, SYP, and postsynaptic density 95, PSD95) were measured by Western blotting. Behavioral assessments indicated that GRe could ameliorate the cognitive impairment of CRS-induced mice, as indicated by increased responses in Y-maze (p < .05), novel objects recognition (p < .01), and step-through passive avoidance tests (p < .01). In addition, GRe treatment significantly decreased the neuronal loss in CRS mice in histological examination. Moreover, chronic GRe treatment significantly ameliorated the down-regulated the expressions of BDNF, Nrf2, heme oxygenase (HO)-1, SYP, and PSD95, as well as up-regulated NLRP3, the adaptor protein ASC, and Caspase-1 protein expression in the hippocampus of CRS-treated mice. Taken together, these findings suggest that GRe has a potential therapeutic effect on memory impairment in C57BL/6J mice exposed to CRS paradigm.