Neuroprotective effect of naringenin is mediated through suppression of NF-κB signaling pathway in experimental stroke.

Oxidative stress and inflammation play an integral role in the pathogenesis of cerebral ischemia that leads to a cascade of events culminating in the death of neurons and their supporting structures. The signaling pathways that link these events are not fully understood. Recent studies have demonstrated a close link between the nuclear factor-κB (NF-κB) signaling pathway and cerebral ischemia/reperfusion (I/R)-induced inflammation. Flavonoids have been suggested to exert human health benefits by anti-oxidant and anti-inflammatory mechanisms. In this study we undertook a pharmacological approach to investigate the ability of naringenin, a potent flavonoid, to prevent oxidative stress and NF-κB-mediated inflammatory brain damage in the rat model of focal cerebral I/R injury. To test this hypothesis, male Wistar rats were pretreated with naringenin once daily for 21 days and then subjected to 1h of middle cerebral artery occlusion followed by 23 h of reperfusion. Naringenin treatment successfully upregulates the antioxidant status, decreases the infarct size and lowers the levels of myeloperoxidase, nitric oxide and cytokines, besides functional recovery returned close to the baseline. Moreover, immunohistochemical and Western blot analyses clearly demonstrated that naringenin treatment limits glial activation and downregulates the NF-κB expression level and their target genes. These results show, prophylactic treatment with naringenin improved functional outcomes and abrogated the ischemic brain injury by suppressing NF-κB-mediated neuroinflammation. The present study suggests that naringenin may be used as a potential neuroprotectant in patients at high risk of ischemic stroke.

Raza SS ，Khan MM ，Ahmad A ，Ashafaq M ，Islam F ，Wagner AP ，Safhi MM ，Islam F ... -  《-》

Ruscogenin reduces cerebral ischemic injury via NF-κB-mediated inflammatory pathway in the mouse model of experimental stroke.

Transient cerebral ischemia initiates a complex series of inflammatory events, which has been associated with an increase in behavioral deficits and secondary brain damage. Ruscogenin is a major steroid sapogenin in the traditional Chinese herb Ophiopogon japonicus that have multiple bioactivities. Recent studies have demonstrated that Ruscogenin is involved in down-regulation of intercellular adhesion molecule-1 (ICAM-1) and nuclear factor-κB (NF-κB) activation in anti-inflammatory pathways. We hypothesized that Ruscogenin protects against brain ischemia by inhibiting NF-κB-mediated inflammatory pathway. To test this hypothesis, adult male mice (C57BL/6 strain) were pretreated with Ruscogenin and then subjected to transient middle cerebral artery occlusion (MCAO)/reperfusion. After 1 h MCAO and 24 h reperfusion, neurological deficit, infarct sizes, and brain water content were measured. Ruscogenin markedly decreased the infarct size, improved neurological deficits and reduced brain water content after MCAO. The activation of NF-κB Signaling pathway was observed after 1h of ischemia and 1h of reperfusion, and Ruscogenin significantly inhibited NF-κB p65 expression, phosphorylation and translocation from cytosol to nucleus at this time point in a dose-dependent manner. NF-κB DNA binding activity, and the expression of NF-κB target genes, including ICAM-1, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), were also suppressed by Ruscogenin pretreatment after 1 h MCAO and 24 h reperfusion. The results indicated that Ruscogenin protected the brain against ischemic damage caused by MCAO, and this effect may be through downregulation of NF-κB-mediated inflammatory responses.

Guan T ，Liu Q ，Qian Y ，Yang H ，Kong J ，Kou J ，Yu B ... -  《-》

Neuroprotective effects of pioglitazone in a rat model of permanent focal cerebral ischemia are associated with peroxisome proliferator-activated receptor gamma-mediated suppression of nuclear factor-κB signaling pathway.

Previous studies have demonstrated that pioglitazone (Piog), a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, inhibits ischemia-induced brain injury. Piog has also been shown to exert anti-inflammatory effects by attenuation of nuclear factor-κB (NF-κB) activation after myocardial ischemia/reperfusion injury. Because NF-κB is known to play a major role in the pathophysiology of brain ischemia, the present study was undertaken to elucidate whether pioglitazone attenuates ischemic neuronal damage through PPARγ-mediated suppression of NF-κB apoptotic signaling pathway. Permanent middle cerebral artery occlusion (pMCAO) model was induced by using an intraluminal filament technique in rats. Piog was administrated i.p. twice (24 h before and at the time of ischemia insult) or once (10 min after ischemia). The neuroprotection of Piog was analyzed by assessing neurological deficits, infarction volume and morphological changes. The inhibition of NF-κB signaling pathway by Piog was evaluated by detecting the nuclear translocation of NF-κB p65 with immunohistochemistry and its target gene p53 by real-time PCR, and the expression of phospholated NF-κB p65 (p- NF-κB p65) in primary cultured neurons and the protein levels of IκBα and p-ERK in the ischemic cortex or striatum with Western blotting analysis. The contribution of a PPARγ mechanism to Piog's inhibitory effects on NF-κB and neuroprotection was evaluated by pretreatment with the PPARγ irreversible antagonist GW9662. In vitro ischemia in cultured primary neurons was induced by the oxygen-glucose deprivation (OGD) and the protective effect of Piog on cultured neurons was measured by lactate dehydrogenase (LDH) assay. Piog (0.5, 1, 2 mg/kg) reduced infarction volume, and improved morphological changes and motor deficits. Piog markedly up-regulated the protein levels of IκBα or p-ERK 6 h or 12 h after ischemia. Piog reduced the nuclear translocation of NF-κB p65 in the ischemic cortical cells and repressed the expression of p53 12 h after ischemia. Pre-treatment with GW9662 blocked Piog-elicited reduction in infarction volume, the increase in protein levels of IκBα and p-ERK, the reduction in the nuclear translocation of NF-κB subunit p65 and the repression of p53 mRNA expression. In addition, Piog attenuated the OGD-induced neuronal damage and inhibited the OGD-induced increases in p- NF-κB p65 in neurons. The present findings suggest that Piog's neuroprotection appears to be associated with PPARγ-mediated suppression of NF-κB signaling pathway.

Zhang HL ，Xu M ，Wei C ，Qin AP ，Liu CF ，Hong LZ ，Zhao XY ，Liu J ，Qin ZH ... -  《-》

Hesperidin ameliorates functional and histological outcome and reduces neuroinflammation in experimental stroke.

Incidence of stroke is considered to be a major cause of death throughout the world. The middle cerebral artery occlusion (MCAO) for 2h followed by 22h of reperfusion model was used in male Wistar rats to study the protection of stroke by hesperidin. Hesperidin administration (50mg/kg b.wt.) once daily for 15days has improved the infarct size, reduced the neurological deficits in terms of behaviors, and protected the elevated level of thiobarbituric acid reactive species (TBARS). A significantly depleted activity of antioxidant enzymes, glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT) and superoxide dismutase (SOD) and content of glutathione (GSH) in MCAO group were protected significantly in MCAO group pretreated with hesperidin. Moreover, inflammatory mediators like TNF-α, IL-1β levels, expression of iNOS and glial fibrillary acidic protein (GFAP) were significantly attenuated in H+MCAO group as compared to MCAO group. In conclusion, prophylactic treatment with hesperidin ameliorated the functional and histological outcomes with elevated endogenous antioxidants status as well as reduced induction of proinflammatory cytokines in MCA occluded rat. We theorized that hesperidin is among the pharmacological agents that reduce free radicals and its associated inflammation and have been found to limit the extent of brain damage following stroke.

Raza SS ，Khan MM ，Ahmad A ，Ashafaq M ，Khuwaja G ，Tabassum R ，Javed H ，Siddiqui MS ，Safhi MM ，Islam F ... -  《-》

Preventive effect of silymarin in cerebral ischemia-reperfusion-induced brain injury in rats possibly through impairing NF-κB and STAT-1 activation.

Silymarin and silibinin are bioactive components isolated from Silybum marianum. They have been reported to exhibit anti-oxidative and anti-inflammatory effects. Many studies revealed that drugs with potent anti-inflammatory potential can protect animals against inflammation-associated neurodegenerative disease, e.g., stroke. In this current work we established an animal model of acute ischemic stroke injury by inducing cerebral ischemic/reperfusion (CI/R) in rats to elucidate whether silymarin or silibinin can protect animals from CI/R injury. Pretreatment with silymarin, but not silibinin, dose-dependently (1-10μg/kg, i.v.) reduced CI/R-induced brain infarction by 16-40% and improved neurological deficits in rats with a stroke. Elevated pathophysiological biomarkers for CI/R-induced brain injury, including lipid peroxidation, protein nitrosylation, and oxidative stress, were all reduced by silymarin. In addition, expression of inflammation-associated proteins (e.g., inducible nitric oxide synthase, cyclooxygenase-2 and myeloperoxidase), and transcriptional factors (e.g., nuclear factor (NF)-kappa B and signal transducer and activator of transcription (STAT)-1), as well as production of proinflammatory cytokine (e.g., interleukin-1β and tumor necrosis factor-α) was all significantly prevented by silymarin. Furthermore, an in vitro study on microglial BV2 cells showed that silymarin could inhibit nitric oxide and superoxide anion production, possibly by interfering with NF-κB nuclear translocation/activation. Likewise, silymarin pretreatment also inhibited IκB-α degradation and NF-κB nuclear translocation in brain tissues of ischemic rats. Our results reveal that silymarin, but not its active component silibinin, protected rats against CI/R-induced stroke injury by amelioration of the oxidative and nitrosative stresses and inflammation-mediated tissue injury through impeding the activation of proinflammatory transcription factors (e.g., NF-κB and STAT-1) in the upregulation of proinflammatory proteins and cytokines in stroke-damaged sites. In conclusion, silymarin displays beneficial effects of preventing inflammation-related neurodegenerative disease, e.g., stroke, which needs further investigation and clinical evidences.

Hou YC ，Liou KT ，Chern CM ，Wang YH ，Liao JF ，Chang S ，Chou YH ，Shen YC ... -  《-》