Inhibitory Effect of Lonicera japonica Thunb. Flower Buds against Glutamate-Induced Cytotoxicity in HT22 Hippocampal Neurons

Abstract

Objectives : In this study, we investigated the neuroprotective effects of ethanol extract of Lonicera japonica flower buds (EELJ) on glutamate-induced neurotoxicity in mouse hippocampus-derived neuronal HT22 cells. Methods : After analyzing the cytoprotective effect of EELJ on glutamate in HT22 cells, the inhibitory effect of apoptosis was studied using flow cytometry. In order to analyze the antioxidant efficacy of EELJ, the levels of reactive oxygen species (ROS) and glutathione (GSH) were investigated, and the effects on the activities of superoxide dismutase (SOD) and catalase (CAT) were also analyzed. Furthermore, the effect of EELJ on the expression of apoptosis regulators such as Bax and Bcl-2 in glutamate-treated HT22 cells was investigated. Results : According the current results, pretreatment with EELJ significantly reduced glutamate-induced loss of cell viability and release of lactate dehydrogenase. EELJ also markedly attenuated glutamate-induced generation of intracellular ROS, which was associated with increased levels of GSH, and activity of SOD and CAT in glutamate-stimulated HT22 cells. In addition, EELJ was strikingly inhibited glutamate-induced apoptosis in HT22 cells. Furthermore, the expression of pro-apoptotic Bax was increased and the expression of anti-apoptotic Bcl-2 was decreased in glutamate-treated HT22 cells, while in the presence of EELJ, their expressions were maintained at the control levels. Conclusions : These findings indicate that EELJ protects glutamate-induced cytotoxicity in HT22 hippocampal neurons through antioxidant activity. Therefore, although identification of biologically active substances of EELJ and re-evaluation through animal experiments is necessary, this natural substance is a promising candidate for further research in preventing and treating oxidative stress-mediated neurodegenerative diseases.

Protective Effect of Lonicera japonica on PM2.5-Induced Pulmonary Damage in BALB/c Mice via the TGF-β and NF-κB Pathway

“…Similar to this study, the administration of polysaccharides of Lonicera japonica showed protective effects on hepatic antioxidant deficits by increasing the expression levels of CAT, SOD, and GSH in type 2 diabetic SD rats [ 31 ]. The ethanol extract of Lonicera japonica flower buds showed neuronal protective effects against glutamate-induced hippocampal cytotoxicity by reducing ROS production and increasing the GSH and SOD levels in HT22 cells [ 32 ]. The aqueous extract of Lonicera japonica , including neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, secoxyloganin, and secologanic acid, showed increases in SOD, CAT, and GSH/oxidized GSH (GSSG) ratios, and reduction of MDA levels by inhibiting the inflammatory response in gastric mucosal tissues [ 33 ].…”