Peoniflorin activates Nrf2/ARE pathway to alleviate the Aβ₍₁₋₄₂₎-induced hippocampal neuron injury in rats

This study was to investigate the effect of peoniflorin on the expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream signal molecules in the hippocampus of Alzheimer’s disease (AD) rats for exploring the mechanism of peoniflorin protecting hippocampal neurons.  AD model rats were established by bilateral intrahippocampal injection of beta-amyloid₍₁₋₄₂₎ (Aβ₍₁₋₄₂₎) and divided randomly into 3 groups: AD model group, peoniflorin low-dose (15 mg·kg⁻¹) group and peoniflorin high-dose (30 mg·kg⁻¹) group.  The vehicle control rats were given bilateral intrahippocampal injection of solvent with the same volume.  After peoniflorin or saline was administered (ip) once daily for 14 days, the hippocampuses of all animals were taken out for measuring the expressions of Nrf2, heme oxygenase-1 (HO-1) and γ-glutamylcysteine synthethase (γ-GCS) mRNA by reverse transcription PCR, determining the contents of glutathione (GSH), malondialdehyde (MDA) and carbonyl protein (CP) using colorimetric method, and for assaying the expressions of neuronal apoptosis inhibitory protein (NAIP) and Caspase-3 by immunohistochemical staining method.  The results showed that peoniflorin markedly increased the expressions of Nrf2, HO-1 and γ-GCS mRNA, enhanced the level of GSH and decreased the contents of MDA and CP in the hippocampus, as compared with the model group.  Peoniflorin also improved the NAIP expression and reduced the Caspase-3 expression in the hippocampus neurons.  In conclusion, peoniflorin protects against the Aβ₍₁₋₄₂₎-mediated oxidative stress and hippocampal neuron injury in AD rats by activating the Nrf2/ARE pathway.