Neuroprotective Effects of Purpurin Against Ischemic Damage via MAPKs, Bax, and Oxidative Stress Cascades in the Gerbil Hippocampus

Woosuk Kim,Hyun Jung Kwon,Kyu Ri Hahn,Hyo Young Jung,Yeo Sung Yoon,Dae Won Kim,Soo Young Choi,In Koo Hwang

doi:10.1007/s12035-021-02642-0

Abstract

Purpurin has various effects, including anti-inflammatory effects, and can efficiently cross the blood–brain barrier. In the present study, we investigated the effects of purpurin on oxidative stress in HT22 cells and mild brain damage in the gerbil hippocampal CA1 region induced by transient forebrain ischemia. Oxidative stress induced by H2O2 was significantly ameliorated by treatment with purpurin, based on changes in cell death, DNA fragmentation, formation of reactive oxygen species, and pro-apoptotic (Bax)/anti-apoptotic (Bcl-2) protein levels. In addition, treatment with purpurin significantly reduced the phosphorylation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase 1/2 (ERK), and p38 signaling in HT22 cells. Transient forebrain ischemia in gerbils led to a significant increase in locomotor activity 1 day after ischemia and significant decrease in number of surviving cells in the CA1 region 4 days after ischemia. Administration of purpurin reduced the travel distance 1 day after ischemia and abrogates the neuronal death in the hippocampal CA1 region 4 days after ischemia based on immunohistochemical and histochemical staining for NeuN and Fluoro-Jade C, respectively. Purpurin treatment significantly decreased the activation of microglia and astrocytes as well as the increases of nuclear factor kappa-light-chain-enhancer of activated B cells p65 in the hippocampal CA1 region 4 days after ischemia and ameliorated the ischemia-induced transient increases of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in the hippocampus 6 h after ischemia. In addition, purpurin significantly alleviated the ischemia-induced phosphorylation of JNK, ERK, and p38 in the hippocampus 1 day after ischemia. Furthermore, purpurin treatment significantly mitigated the increases of Bax in the hippocampus 1 day after ischemia and the lipid peroxidation based on malondialdehyde and hydroperoxides levels 2 days after ischemia. These results suggest that purpurin can be one of the potential candidates to reduce neuronal damage and inflammatory responses after oxidative stress in HT22 cells or ischemic damage in gerbils.

Highlights

Materials and MethodsIschemic stroke is a life-threatening disease that affects approximately 15 million people worldwide annually [1]
In the vehicle-treated ischemic group, the ratios of p-Jun N-terminal kinase (JNK)/JNK, p-extracellular signal-regulated kinase 1/2 (ERK)/ERK, and p-p38/p38 were significantly increased to 221.8%, 692.4%, and 223.9% of control group, respectively, naïve forms of mitogen-activated protein kinases (MAPKs) showed similar levels compared to respective control group
We investigated the role of purpurin against oxidative stress induced by H 2O2 in HT22 cells and against ischemic damage in gerbils

Summary

Introduction

Materials and MethodsIschemic stroke is a life-threatening disease that affects approximately 15 million people worldwide annually [1]. We elucidated the effects of purpurin and its mechanisms based on H 2O2-induced oxidative stress in HT22 cells and ischemia-induced neuronal damage in the gerbil hippocampal CA1 region. To elucidate the mechanisms of purpurin’s effects against ischemic damage, animals (n = 5 in each group) were euthanized with 75 mg/kg alfaxalone and 10 mg/kg xylazine 6 h and 4 days after ischemia/reperfusion, when pro-inflammatory cytokine levels were significantly increased and returned to control levels, respectively [29, 30].

Results

Conclusion