Neuroprotective effects of orientin on oxygen-glucose deprivation/reperfusion-induced cell injury in primary culture of rat cortical neurons

Abstract

Orientin (luteolin-8-C-glucoside) is a phenolic compound found abundantly in millet, juice, and peel of passion fruit and has been shown to have antioxidant properties. In the present study, we explored the effects of orientin on oxygen-glucose deprivation/reperfusion (OGD/RP)-induced cell injury in primary culture of rat cortical neurons using an in vitro model of neonatal ischemic brain injury. The reduced cell viability and elevated lactate dehydrogenase leakage were observed after OGD/RP exposure, which were then reversed by orientin (10, 20, and 30 µM) pretreatment in a dose-dependent manner. Additionally, OGD/RP treatment resulted in significant oxidative stress, accompanied by enhanced intracellular reactive oxygen species (ROS) generation, and obvious depletion in the activities of intracellular Mn-superoxide dismutase, catalase, and glutathione peroxidase antioxidases. However, these effects were dose dependently restored by orientin pretreatment. We also found that orientin pretreatment dose dependently suppressed [Ca] increase and mitochondrial membrane potential dissipation caused by OGD/RP in primary culture of rat cortical neurons. Western blot analysis showed that OGD/RP exposure induced a distinct decrease of Bcl-2 protein and a marked elevation of Bax, caspase-3, and cleaved caspase-3 proteins; whereas these effects were dose dependently reversed by orientin incubation. Both the caspase-3 activity and the apoptosis rate were increased under OGD/RP treatment, but was then dose dependently down-regulated by orientin (10, 20, and 30 µM) incubation. Moreover, orientin pretreatment dose dependently inhibited OGD/RP-induced phosphorylation of JNK and ERK1/2. Notably, JNK inhibitor SP600125 and ERK1/2 inhibitor PD98059 also dramatically attenuated OGD/RP-induced cell viability loss and ROS generation, and further, orientin failed to protect cortical neurons with the interference of JNK activator anisomycin or ERK1/2 activator FGF-2. Taken together, these results demonstrated that orientin has significant neuroprotective effects against OGD/RP-induced cell injury via JNK and ERK1/2 signaling pathways in primary culture of rat cortical neurons. Impact statement Orientin has been used in traditional eastern medicine and reported to possess antioxidant properties. However, the effects of orientin on neonatal ischemic brain injury and the underlying mechanisms involved have not been studied. Our results showed that orientin exerts significant neuroprotective effects on cell injury caused by oxygen-glucose deprivation/reperfusion via the JNK and ERK1/2 signaling pathways in primary culture of rat cortical neurons, implying the potential therapeutic application of orientin via the suppression of oxidative stress and cell apoptosis. This research suggested that orientin may be used as a therapeutic and preventive option for newborn cerebral ischemia/reperfusion injury.

Erythropoietin protects neurons from apoptosis via activating PI3K/AKT and inhibiting Erk1/2 signaling pathway

“…The Erk1/2 signaling pathway has a close relationship with neuronal cells differentiation and proliferation; however, previous reports exhibited controversial observations about the role of Erk1/2 in the process of neuroprotection. Studies from Gong et al (2014) and Tian et al (2018) showed that activation of Erk1/2 after OGD or OGD/PR was observed characterized by increased expression of p-ERK1/2. In contrast, some studies demonstrated that Erk1/2 activation contributed to the protective effects of some neuroprotectants.…”

Mangifera indica L. Leaf Extract in Combination With Luteolin or Quercetin Enhances VO2peak and Peak Power Output, and Preserves Skeletal Muscle Function During Ischemia-Reperfusion in Humans

“…Both enzyme activities, XO and NOX, play a critical role in RONS generation during intense exercise (Morales-Alamo and Calbet, 2014 ) and ischemia/reperfusion events (Berry and Hare, 2004 ). Luteolin mitigates ischemia/reperfusion damage in cell cultures (Tian et al, 2018 ) and animals (Karakaş et al, 2014 ; Hong et al, 2017 ; Liu et al, 2017 ; Luo et al, 2017 ; Du et al, 2018 ).…”

Neuroprotective Role of Hypothermia in Hypoxic-ischemic Brain Injury: Combined Therapies using Estrogen

“…In addition, JNK inhibitor SP600125 and ERK1/2 inhibitor PD98059 ameliorated OGD/RP-induced cell death and ROS generation. Further, orientin failed to protect cortical neurons with the JNK activator anisomycin or with the ERK1/2 activator FGF-2 [6], showing that the neuroprotective effects of orientin against OGD/RP-induced damage depend on down-regulation of JNK and ERK1/2 signaling pathways [6]. In a model of OGD/R injury in a primary co-culture of rat cortical capillary endothelial cells, astrocytes and neurons to allow simultaneous observations in the same system, it was found that pretreatment with Ginkgo biloba extract or Ginkgolide B increased neuronal viability, ameliorated cell injury, and inhibited cellular apoptotic rate through Bcl-2 and Bcl-2-associated X protein (Bax) expression [7].…”

“…Hypoxic-ischemic (HI) brain injury is mainly characterized by decreasing O2 concentration and blood flow, which lead to an inefficient supply of nutrients to the brain. This pathophysiological conditions lead to cell death by energy depletion and increased free radical generation [4], as it is observed in perinatal asphyxia (PA) and ischemic-stroke (IS) [5][6][7]. PA and IS represent one of the main causes of mortality and morbidity in children and adults worldwide [8,9].…”