Quercetin attenuates cerebral ischemic injury by inhibiting ferroptosis via Nrf2/HO-1 signaling pathway.

AIMS: Ischemic stroke is a severe cerebrovascular disease in which neuronal death continually occurs through multiple forms, including apoptosis, autophagy, pyroptosis and ferroptosis. Quercetin (QRC), as a natural flavonoid compound, has been reported to have pharmacological effects on ischemic injury accompanied by unclear anti-ferroptotic mechanisms. This study is designed to investigate the therapeutic effects of QRC against ferroptosis in ischemic stroke. MATERIALS AND METHODS: In vivo, the model of MCAO rats were used to assess the protective effect of QRC on cerebral ischemic. Additionally, we constructed oxidative stressed and ferroptotic cell models to explore the effects and mechanisms of QRC on ferroptosis. The related proteins were analysed by western blotting, immunohistochemical and immunofluorescence techniques. RESULTS: The experiments demonstrated that QRC improves neurological deficits, infarct volume, and pathological features in MCAO rats, also increased the viability of HT-22 cells exposed to H2O2 and erastin. These results, including MDA, SOD, GSH, ROS levels and iron accumulation, indicated that QRC suppresses the generation of lipid peroxides and may involve in the regulatory of ferroptosis. Both in vitro and in vivo, QRC was found to inhibit ferroptosis by up-regulating GPX4 and FTH1, as well as down-regulating ACSL4. Furthermore, we observed that QRC enhances the nuclear translocation of Nrf2 and activates the downstream antioxidative proteins. Importantly, the effect of QRC on ferroptosis can be reversed by the Nrf2 inhibitor ML385. CONCLUSIONS: This study provides evidence that QRC has a neuroprotective effect by inhibiting ferroptosis, demonstrating the therapeutic potential for cerebral ischemic stroke.

Effect of vanillic acid on pentylenetetrazole-kindled rats: Nrf2/HO-1, IGF-1 signaling pathways cross talk.

Vanillic acid (VA) exhibited antioxidant and neuroprotective properties in some neurodegenerative disorders. So, the current study examined the neuroprotective potential of VA as an antiepileptic agent in pentylenetetrazole (PTZ)-induced epileptic rats and the prospective role of Insulin like growth factor-1 (IGF-1) and nuclear factor-2 erythroid-related factor-2 (Nrf2)/heme oxygenase-1 (HO-1) pathway in this respect. Thirty male albino rats were equally subdivided into 3 groups; (1) normal control (NC) group, (2) PTZ-group: received PTZ (50 mg/Kg, i.p. every other day) for 14 days, and (3) PTZ + VA group: received PTZ and VA (50 mg/Kg daily for 2 weeks). The seizure score and latency were evaluated after PTZ injection. Also, the markers of oxidative stress (malondialdehyde (MDA), catalase, and reduced glutathione (GSH)), histopathological examination, the expression of glial fibrillary acidic protein (GFAP) (a marker of astrocytes) IGF-1, Nrf2, and HO-1 were assessed in the brain tissues by the end of the experiment. PTZ caused significant decrease in seizure latency and significant increase in seizure score by the end of the experiment (p < 0.01). This was associated with significant increase in MDA and GFAP with significant decrease in GSH, total antioxidant capacity (TAC) and IGF-1 in brain tissues compared to normal group (p < 0.01). On the other hand, treatment with VA caused significant attenuation in PTZ-induced seizures which was associated with significant improvement in oxidative stress markers and downregulation in GFAP and upregulation of Nrf2, HO-1 and IGF-1 in CA3 hippocampal region (p < 0.01). VA showed neuroprotective and anti-epileptic effects against PTZ-induced epilepsy which probably might be due to its antioxidant properties and upregulation of Nrf2/HO-1 pathway and IGF-1.

The upregulation of Nur77 decreases ketamine-induced hippocampal neurons toxicity in rats.

Ketamine is clinically used as a narcotic. However, ketamine has certain deficits and produces toxicity to neurons. As a member of the NR4A receptor subfamily, Nur77 decreases neurodegenerative disorders. The study aims to investigate the effects of upregulated Nur77 on ketamine-induced rat hippocampal neurons damage and the active mechanism. Neurons were obtained from rat hippocampal and identified by immunofluorescence assays. The treatment groups contained ketamine group, Nur77 group, ketamine + Nur77 group and ketamine + L-cam group. Neurons apoptosis and reactive oxygen species (ROS) were determined by a related kit using flow cytometry. Enzyme NAD(P)H quinone oxidoreductase 1 (NQO1), enzyme heme oxygenase 1 (HO1), Nur77, the expression of Bax, Bcl-2 and cleaved-caspase-3 and inflammatory cytokines were measured using western blot assays and reverse transcription-quantitative PCR (RT-qPCR) assays. Ketamine-induced neurons apoptosis; however, Nur77 decreased ketamine-induced neurons apoptosis. A low level of ROS was observed in two combination groups. Neurons treated by ketamine only had the lowest levels of Nur77, NQO1 and HO1, compared with other treatment groups. The levels of Bax and cleaved-caspase-3 in two combination groups were lower than those in the ketamine group. Furthermore, the ketamine group had higher levels of tumor necrosis factor alpha, IL-1ß and IL-6 but the lowest level of IL-4. Upregulated Nur77 reduced the ketamine-induced toxicity in neurons. The mechanism of Nur77 involved antioxidation, apoptosis signaling pathway and inflammation signaling pathway. Our study provides a novel therapy that could attenuate ketamine-induced toxicity.

Involvement of Nrf-2/HO-1 pathway in sevoflurane-induced cognitive improvement in rats with traumatic brain injury.

Traumatic brain injury (TBI) is an increasingly common emergency disease that usually leads to prolonged physical and cognitive impairments. In this study, we investigated if sevoflurane could induce cognitive improvement in TBI rats. Rats were subjected to head trauma induced by a fluid percussion device. A two-hour exposure to 3% sevoflurane was performed in a chamber immediately after TBI. Sevoflurane inhalation reduced the neurological and cognitive deficits induced by TBI with ameliorated synaptic injuries in the hippocampus. Moreover, after sevoflurane treatment, the expression of nuclear factor erythroid-2-related factor-2 (Nrf-2) and hemeoxygenase-1 (HO-1) in the hippocampus was enhanced 1 d after TBI and maintained at high levels 14 days later, and oxidative stress induced by TBI was inhibited. However, the HO-1 inhibitor, Zinc protoporphyrin (ZnPP), used to demonstrate the involvement of HO-1, suppressed the protective effect of sevoflurane. These results indicate that sevoflurane administered immediately after TBI may protect against TBI-induced synaptic and cognitive impairments by promoting the antioxidant Nrf-2/HO-1 pathway. Sevoflurane may be a promising anesthetic for patients with TBI.

Brain-targeted hypoxia-inducible factor stabilization reduces neonatal hypoxic-ischemic brain injury.

Hypoxia-inducible factor-1α (HIF1α) is a major regulator of cellular adaptation to hypoxia and oxidative stress, and recent advances of prolyl-4-hydroxylase (P4H) inhibitors have produced powerful tools to stabilize HIF1α for clinical applications. However, whether HIF1α provokes or resists neonatal hypoxic-ischemic (HI) brain injury has not been established in previous studies. We hypothesize that systemic and brain-targeted HIF1α stabilization may have divergent effects. To test this notion, herein we compared the effects of GSK360A, a potent P4H inhibitor, in in-vitro oxygen-glucose deprivation (OGD) and in in-vivo neonatal HI via intracerebroventricular (ICV), intraperitoneal (IP), and intranasal (IN) drug-application routes. We found that GSK360A increased the erythropoietin (EPO), heme oxygenase-1 (HO1) and glucose transporter 1 (Glut1) transcripts, all HIF1α target-genes, and promoted the survival of neurons and oligodendrocytes after OGD. Neonatal HI insult stabilized HIF1α in the ipsilateral hemisphere for up to 24 h, and either ICV or IN delivery of GSK360A after HI increased the HIF1α target-gene transcripts and decreased brain damage. In contrast, IP-injection of GSK360A failed to reduce HI brain damage, but elevated the risk of mortality at high doses, which may relate to an increase of the kidney and plasma EPO, leukocytosis, and abundant vascular endothelial growth factor (VEGF) mRNAs in the brain. These results suggest that brain-targeted HIF1α-stabilization is a potential treatment of neonatal HI brain injury, while systemic P4H-inhibition may provoke unwanted adverse effects.

Sitagliptin protects liver against aflatoxin B1-induced hepatotoxicity through upregulating Nrf2/ARE/HO-1 pathway.

Dipeptidyl peptidase-4 inhibitor (DPP-4 inhibitor) such as sitagliptin has been presented as antidiabetic drugs and has numerous restorative advantages over different diseases; however, its defensive role against aflatoxin b1 (AFB1) liver toxicity has not been previously examined. Wistar rats (65 weeks, male) were utilized in the investigation. Animals were divided into five different groups (n = 10): control; AFB1; AFB1 + Sita (50); AFB1 + Sita (100); and Sita (100). Sitagliptin significantly (*p ≤ .05, **p ≤ .01, and ***p ≤ .001) altered the levels of various serum liver enzymes (lactate dehydrogenase, alkaline phosphate, aspartate aminotransferase, and alanine aminotransferase). It decreased the concentration of an oxidative stress marker, that is, malondialdehyde and increased the level of antioxidant enzymes such as reduced glutathione, catalase, superoxide dismutase, and glutathione peroxidase in AFB1-administered rats. It also improved the Nrf2 expression and HO-1 level in AFB1-intoxicated rats. This investigation discusses innovative evidence on the protective role of sitagliptin against AFB1-induced hepatotoxicity in rats.

Protective effects of epigallocatechin gallate against ischemia reperfusion injury in rat skeletal muscle via activating Nrf2/HO-1 signaling pathway.

AIMS: Previous studies have demonstrated that epigallocatechin gallate (EGCG) had certain protective effects on myocardial and renal ischemia reperfusion (I/R) injury. We aimed to research the special effects and underling mechanisms of EGCG on skeletal muscle I/R injury. MAIN METHOD: We established an experimental rat model of I/R skeletal muscle injury and treated with different doses of EGCG. Hematoxylin eosin staining, TUNEL assay, ELISA, qRT-PCR and Western blotting were used to evaluate the effects of EGCG. KEY FINDINDS: EGCG significantly improved skeletal muscle function of I/R injury rats. Moreover, EGCG had positive effects on decreasing apoptosis of skeletal muscle tissues, alleviating oxidative stress damage and suppressing the production of inflammatory cytokines. Further, EGCG had positive effects on activating Nrf2/HO-1 signaling pathway. SIGNIFICANCE: EGCG might be a powerful candidate compound for alleviating I/R injury in rat skeletal muscle.

Effect of levocarnitine on cerebral ischemia-reperfusion rats via activating Nrf2/ARE signaling pathway.

OBJECTIVE: Levocarnitine plays a crucial role in the metabolism of organisms. The aim of this study was to explore the impact of Levocarnitine on cerebral ischemia-reperfusion (I/R) rats and the underlying mechanism. MATERIALS AND METHODS: Cerebral I/R model was first successfully established. Two groups were set up, including drug group (I/R + Levocarnitine group) and control group (I/R group). The influences of Levocarnitine on brain injury and oxidative stress in cerebral I/R rats were evaluated. Furthermore, the impacts of Levocarnitine on the nuclear factor E2-related factor 2 (Nrf2)/antioxidant responsive element (ARE) signaling pathway and neuronal apoptosis in rats were detected. RESULTS: Compared with I/R group, I/R + Levocarnitine group exhibited markedly lowered neurological deficit score and cerebral infarct volume. However, superoxide dismutase (SOD) and notably decreased malondialdehyde (MDA) were significantly up-regulated in I/R + Levocarnitine group. This suggested that Levocarnitine could relieve cerebral nerve injury and oxidative stress in cerebral I/R rats. Additionally, in I/R + Levocarnitine group, the protein expressions of Nrf2, heme oxygenase-1 (HO-1), and B-cell lymphoma 2 (Bcl-2) were significantly up-regulated, whereas cleaved Caspase-3 (c-Caspase-3) was notably down-regulated. Furthermore, neuronal apoptosis in cerebral I/R rats was remarkably inhibited. CONCLUSIONS: Levocarnitine alleviates brain injury and neuronal apoptosis in cerebral I/R rats by activating the Nrf2/ARE signaling pathway.

[The protective effects of lycium barbarum polysaccharides on retinal neurons in diabetic rats and its mechanism].

OBJECTIVE: To clarify whether lycium barbarum polysaccharides (LBP) have protective effects on retina neuronal cells in diabetic rats and to identify the related mechanism involved in this process. METHODS: Eighteen SD rats were randomly divided into 3 groups ( n= 6): normal control group (NC), diabetes mellitus group (DM) and LBP-treatment group (DM+LBP). The diabetic rat model was induced by single intraperitoneal injection of streptozotocin (STZ). The rats in DM+LBP group were treated with LBP at the dose of 1 mg/kg by gavage, once a day for 12 weeks. After the treatment, the weight and blood glucose, the generation of reactive oxygen species (ROS), the surviving retinal ganglion cells (RGCs) and amacrine cells and the protein expressions of nuclear factor E2-related factor 2 (Nrf2) and the heme oxygenase-1 (HO-1) were detected. RESULTS: The successful rate of diabetic model was 100%. Compared with NC group, the rats of DM group caused weight loss, elevated blood glucose, a marked increase of ROS generation and a significant decrease in the number of RGCs and amacrine cells (P＜0.01), and these effects were diminished or abolished by LBP treatment. Meanwhile, LBP significantly increased the expressions of Nrf2 and HO-1 in the retinas of diabetic rats (P＜0.01). CONCLUSION: LBP can improve retinal oxidative stress and exert beneficial neuroprotective effects in diabetic rats, and its mechanism may be associated with the activation of the Nrf2/HO-1 antioxidant pathway.

Synthesis and Target Identification of a Novel Electrophilic Warhead, 2-Chloromethylquinoline.

Despite its power in identifying highly potent ligands for select protein targets, conventional medicinal chemistry is limited by its low throughput and lack of proteomic selectivity information. We seek to develop a chemoproteomic approach for discovering covalent ligands for protein targets in an unbiased, high-throughput manner. Tripartite probe compounds composed of a heterocyclic core, an electrophilic "warhead", and an alkyne tag have been designed and synthesized for covalently labeling and identifying targets in cells. We have developed a novel condensation reaction to prepare 2-chloromethylquinoline (2-CMQ), an electrophilic heterocycle. These chloromethylquinolines potently and covalently bind to a number of cellular protein targets, including prostaglandin E synthase 2 (PTGES2), a critical regulator of cell proliferation, apoptosis, angiogenesis, inflammation, and immune surveillance. The 2-CMQs that we have developed here are novel PTGES2 binders that have the potential to serve as therapies for the treatment of human diseases such as inflammation.

Sitagliptin improves renal function in diabetic nephropathy in male Sprague Dawley rats through upregulating heme oxygenase-1 expression.

PURPOSE: Oxidative stress is an important mechanism for diabetic nephropathy. Studies showed that hemo oxygenase-1 (HO-1) expression in renal tissue of patients with diabetic nephropathy has upregulated, while the HO-1 can protect the body through anti-oxidative stress. The study aimed to preliminarily explore the molecular mechanism by observing the effect of Sitagliptin on HO-1 expression in renal tissue of rats with diabetic nephropathy. METHODS: The diabetic nephropathy rat model was established by STZ injection followed by intraperitoneal injection of sitagliptin with different concentrations. The mRNA expressions of HO-1 were detected by real-time PCR and Western blot and HO-1 enzyme activity change was detected by colorimetry. Human renal mesangial cell (HRMC) were cultured in vitro with high glucose concentration (30 µmol/L), phosphatidylinositol-3-kinase (PI3K) level and nuclear factor erythroid-2-related factor (Nrf2) content in cytoplasm and cell nucleus were observed before and after treatment with sitagliptin, as well as the action of in meditating HO-1 expression. RESULTS: HO-1 mRNA, protein level, and HO-1 enzyme activity in renal tissue of rats with diabetic nephropathy were significantly increased after treatment with sitagliptin (P < 0.05). As comparison, the 24 h urinary microalbumin, creatinine, and boold urea nitrogen were all decreased after treatment of sitagliptin (P < 0.05). Similar results were observed after CoPP (an agonist of HO-1) treatment (P < 0.05). In contrast, ZnPP, an inhibitor of HO-1, significantly abrogated the inhibitory effect of sitagliptin (P < 0.05). Phosphorylation of PI3K and Nrf2 nuclear translocation under high-glucose concentration condition was induced by sitagliptin in HRMC. HO-1 expression was suppressed by pretreating HRMC with PI3K inhibitor or RNA interference. CONCLUSIONS: Sitagliptin may induce HO-1 expression via activation of PI3K and Nrf2 in rats with diabetic nephropathy; HO-1 can improve the oxidative stress of diabetic nephropathy, eventually protect from diabetic nephropathy.

Heme Oxygenase Inhibition Sensitizes Neuroblastoma Cells to Carfilzomib.

Neuroblastoma (NB) is an embryonic malignancy affecting the physiological development of adrenal medulla and paravertebral sympathetic ganglia in early infancy. Proteasome inhibitors (PIs) (i.e., carfilzomib (CFZ)) may represent a possible pharmacological treatment for solid tumors including NB. In the present study, we tested the effect of a novel non-competitive inhibitor of heme oxygenase-1 (HO-1), LS1/71, as a possible adjuvant therapy for the efficacy of CFZ in neuroblastoma cells. Our results showed that CFZ increased both HO-1 gene expression (about 18-fold) and HO activity (about 8-fold), following activation of the ER stress pathway. The involvement of HO-1 in CFZ-mediated cytotoxicity was further confirmed by the protective effect of pharmacological induction of HO-1, significantly attenuating cytotoxicity. In addition, HO-1 selective inhibition by a specific siRNA increased the cytotoxic effect following CFZ treatment in NB whereas SnMP, a competitive pharmacological inhibitor of HO, showed no changes in cytotoxicity. Our data suggest that treatment with CFZ produces ER stress in NB without activation of CHOP-mediated apoptosis, whereas co-treatment with CFZ and LS1/71 led to apoptosis activation and CHOP expression induction. In conclusion, our study showed that treatment with the non-competitive inhibitor of HO-1, LS1 / 71, increased cytotoxicity mediated by CFZ, triggering apoptosis following ER stress activation. These results suggest that PIs may represent a possible pharmacological treatment for solid tumors and that HO-1 inhibition may represent a possible strategy to overcome chemoresistance and increase the efficacy of chemotherapic regimens.

[Hemin regulates the expression of nuclear factor kappa B of heme oxygenase -1 in hepatic fibrosis].

Objective: To observe the therapeutic effects and related mechanism of hemin on the progression of hepatic fibrosis in rats. Methods: Sixty male Wistar rats were randomly divided into normal control group, 4-week model group, 6-week model group, hemin inhibitor zinc protoporphyrin-IX (ZnPP-IX) intervention group and hemin intervention group. Hemin intervention group in complex liver fibrosis model was intraperitonealy administered ZnPP-IX or hemin every other day for 2 weeks from the fourth week. The mRNA expression of HO-1, α-smooth muscle actin (α-SMA) and nuclear factor-κB (NF-κB) in the liver tissue was detected by real-time polymerase chain reaction. Immunohistochemistry was used to detect HO-1 and localization of α-SMA expression. Serum hyaluronic acid, propeptide of type III collagen and hepatic transforming growth factor beta (TGFß), and interleukin 6 (IL-6) expressions were detected by enzyme-linked immunosorbent assay. The content of hydroxyproline in hepatic tissues was measured by alkaline hydrolysis method. One-way ANOVA was used to compare the mean of each group. The difference between the two groups was compared by independent samples t- test. P-values < 0.05 was considered statistically significant. Results: Compared with model groups and ZnPP-IX intervention group, Hemin's intervention significantly increased the expression of HO-1 mRNA (P < 0.01) and protein distribution in liver tissues, while the expression of alpha-SMA mRNA was significantly decreased (P < 0.05) in portal space and areas around the fibrotic septum, and hepatic sinus. Hyp content and serum hyaluronic acid and propeptide of type III collagen decreased significantly (P < 0.05). Meanwhile, NF-κB p65 mRNA expression and the downstream production of TGFß and IL-6 in Hemin intervention group were also inhibited (P < 0.05). Conclusion: Hemin can significantly inhibit the progression of hepatic fibrosis in rats by up-regulating HO-1 expression, and the inhibiting activity of NF-κB p65 leads to downstream of the inflammatory factors.

Honokiol Alleviates Oxidative Stress-Induced Neurotoxicity via Activation of Nrf2.

Honokiol (Hon), a polyphenol and main active ingredient from the bark of Magnolia officinalis, has been documented as having multiple pharmacological functions, including neuroprotection. However, the mechanisms underlying its neuroprotective effects are not well-defined. In this study, we reported that Hon attenuates the H2O2- or 6-hydroxydopamine (6-OHDA)-induced apoptosis of PC12 cells by increasing the glutathione level and upregulating a multitude of cytoprotective proteins, including heme oxygenase 1, NAD(P)H:quinone oxidoreductase 1, thioredoxin 1, and thioredoxin reductase 1. Further studies reveal that Hon promotes transcription factor Nrf2 nuclear translocation and activation. Moreover, the cytoprotection of Hon was antagonized by silence of Nrf2 expression, highlighting the fact that Nrf2 is critically engaged in the cellular functions of Hon. Taken together, our study identified that Hon is an effective agonist of Nrf2 in the neuronal system and displays potent neuroprotection against oxidative stress-mediated PC12 cell damage. These findings indicate that Hon is promising for further development as a therapeutic drug against oxidative stress-related neurodegenerative disorders.

Minocycline Effects on Intracerebral Hemorrhage-Induced Iron Overload in Aged Rats: Brain Iron Quantification With Magnetic Resonance Imaging.

BACKGROUND AND PURPOSE: Brain iron overload is a key factor causing brain injury after intracerebral hemorrhage (ICH). This study quantified brain iron levels after ICH with magnetic resonance imaging R2* mapping. The effect of minocycline on iron overload and ICH-induced brain injury in aged rats was also determined. METHODS: Aged (18 months old) male Fischer 344 rats had an intracerebral injection of autologous blood or saline, and brain iron levels were measured by magnetic resonance imaging R2* mapping. Some ICH rats were treated with minocycline or vehicle. The rats were euthanized at days 7 and 28 after ICH, and brains were used for immunohistochemistry and Western blot analyses. Magnetic resonance imaging (T2-weighted, T2* gradient-echo, and R2* mapping) sequences were performed at different time points. RESULTS: ICH-induced brain iron overload in the perihematomal area could be quantified by R2* mapping. Minocycline treatment reduced brain iron accumulation, T2* lesion volume, iron-handling protein upregulation, neuronal cell death, and neurological deficits (P<0.05). CONCLUSIONS: Magnetic resonance imaging R2* mapping is a reliable and noninvasive method, which can quantitatively measure brain iron levels after ICH. Minocycline reduced ICH-related perihematomal iron accumulation and brain injury in aged rats.

Eff ects of hemin, a heme oxygenase-1 inducer in L-arginine-induced acute pancreatitis and associated lung injury in adult male albino rats.

OBJECTIVE: The aim of the current study was to assess the protective outcome of hemin, a heme oxygenase-1 (HO-1) inducer on L-arginine-induced acute pancreatitis in rats. Acute pancreatitis (AP) is considered to be a critical inflammatory disorder with a major impact on the patient health. Various theories have been recommended regarding the pathophysiology of AP and associated pulmonary complications. METHODS: Twenty-four adult male albino rats were randomly divided into four groups: control group, acute pancreatitis (AP), hemin pre-treated AP group, and hemin post-treated AP group. RESULTS: Administration of hemin before induction of AP significantly attenuated the L-arginine- induced pancreatitis and associated pulmonary complications characterized by the increasing serum levels of amylase, lipase, tumor necrosis factor-α, nitric oxide, and histo-architectural changes in pancreas and lungs as compared to control group. Additionally, pre-treatment with hemin significantly compensated the deficits in total antioxidant capacities and lowered the elevated malondialdehyde levels observed with AP. On the other hand, post-hemin administration did not show any protection against L-arginine-induced AP. CONCLUSIONS: The current study indicates that the induction of HO-1 by hemin pre-treatment significantly ameliorated the L-arginine-induced pancreatitis and associated pulmonary complications may be due to its anti-inflammatory and antioxidant properties.

Activation of the nuclear factor E2-related factor 2/anitioxidant response element alleviates the nitroglycerin-induced hyperalgesia in rats.

BACKGROUND: Antioxidants have been proven to weaken hyperalgesia in neuropathic pain. Endogenous antioxidant defense system may have a role in the prevention of hyperalgesia in migraine. In this study, we aimed to evaluate the role of nuclear factor E2-related factor 2/antioxidant response element (Nrf2/ARE) pathway in regulating the activation of the trigeminovascular system (TGVS) and hypersensitivity in nitroglycerin (NTG)-induced hyperalgesia rats. METHODS: The expression levels of Nrf2, HO, HO1, and NQO1 in the trigeminal nucleus caudalis (TNC) were detected by western blot. Immunofluorescence was used to demonstrate the cell-specific localization of Nrf2 in TNC. Sulforaphane, a Nrf2 activator, was administered to NTG-induced rats. Then, the number of c-Fos- and nNOS-immunoreactive neurons in TNC was evaluated using immunofluorescence, and c-Fos and nNOS protein levels were quantified using western blot. Von Frey hair testing was used to evaluate the tactile thresholds of rats at different time points in different groups. RESULTS: Total cellular and nuclear levels of the proteins Nrf2, HO1, and NQO1 were elevated in TNC after NTG injection, and Nrf2 was found to be located in the nucleus and cytoplasm of the neurons. Sulforaphane pretreatment significantly increased the nuclear Nrf2, HO1, and NQO1 levels in TNC. In addition, sulforaphane exposure effectively inhibited the expression of nNOS and c-Fos, reduced the number of nNOS and c-Fos immunoreactive neurons in TNC, and attenuated the tactile thresholds induced by NTG injection. CONCLUSION: Oxidative stress was involved in nitroglycerin-induced hyperalgesia. Activation of the Nrf2/ARE pathway inhibited the activation of TGVS and prevented the induction of hyperalgesia. Sulforaphane might therefore be an effective agent for hyperalgesia. Further studies are needed to discover the underlying mechanisms of the process.

Hydrogen Sulfide and Carbon Monoxide Protect Gastric Mucosa Compromised by Mild Stress Against Alendronate Injury.

BACKGROUND: Alendronate is an inhibitor of osteoclast-mediated bone resorption, but its clinical utility is limited due to gastrointestinal complications including bleeding erosions. AIMS: We studied whether potent vasodilators hydrogen sulfide (H2S) and carbon monoxide (CO) can protect against alendronate-induced gastric lesions in rats exposed to mild stress. METHODS: Three series (A, B, and C) of Wistar rats received alendronate (150-700 mg/kg i.g., series A) with or without NaHS (5 mg/kg), H2S donor or CORM-2 (5 mg/kg) releasing CO administered i.g. 30 min before alendronate administration (series B) in rats exposed for 3 days before alendronate administration to mild stress (series C). The area of gastric lesions was assessed by planimetry, the gastric blood flow (GBF) was determined by H2-gas clearance technique, and H2S production via CSE/CBS/3-MST activity and the gastric expression of HO-1, HO-2, HIF-1α, NF-κB, iNOS, COX-2, IL-1ß, TNF-α, GPx-1 and SOD-2 were analyzed by qPCR or Western blot. RESULTS: Alendronate dose-dependently produced gastric mucosal lesions and significantly decreased GBF, and these effects were exacerbated by mild stress. NaHS and CORM-2 significantly reduced the alendronate-induced gastric lesions in non-stressed and stressed animals, but only NaHS but not CORM-2 raised H2S production. NaHS and CORM-2 inhibited gastric expression of HIF-1α protein and HO-1, HIF-1α, NF-κB, COX-2, iNOS, IL-1ß, TNF-α mRNAs but failed to affect those of HO-2, GPx-1, and SOD-2. CONCLUSION: Both H2S and CO released from their donors, NaHS and CORM-2, protect gastric mucosa compromised by stress against alendronate-induced gastric damage via mechanism involving downregulation of HIF-1α, NF-κB and proinflammatory factors COX-2, iNOS, IL-1ß, and TNF-α.

Minocycline Attenuates Iron-Induced Brain Injury.

Iron plays an important role in brain injury after intracerebral hemorrhage (ICH). Our previous study found minocycline reduces iron overload after ICH. The present study examined the effects of minocycline on the subacute brain injury induced by iron. Rats had an intracaudate injection of 50 µl of saline, iron, or iron + minocycline. All the animals were euthanized at day 3. Rat brains were used for immunohistochemistry (n = 5-6 per each group) and Western blotting assay (n = 4). Brain swelling, blood-brain barrier (BBB) disruption, and iron-handling proteins were measured. We found that intracerebral injection of iron resulted in brain swelling, BBB disruption, and brain iron-handling protein upregulation (p < 0.05). The co-injection of minocycline with iron significantly reduced iron-induced brain swelling (n = 5, p < 0.01). Albumin, a marker of BBB disruption, was measured by Western blot analysis. Minocycline significantly decreased albumin protein levels in the ipsilateral basal ganglia (p < 0.01). Iron-handling protein levels in the brain, including ceruloplasmin and transferrin, were reduced in the minocycline co-injected animals. In conclusion, the present study suggests that minocycline attenuates brain swelling and BBB disruption via an iron-chelation mechanism.