Nicotinamide riboside kinase-2 alleviates ischemia-induced heart failure through P38 signaling

Nicotinamide riboside kinase-2 (NRK-2), a muscle-specific β1 integrin binding protein, predominantly expresses in skeletal muscle with a trace amount expressed in healthy cardiac tissue. NRK-2 expression dramatically increases in mouse and human ischemic heart however, the specific role of NRK-2 in the pathophysiology of ischemic cardiac diseases is unknown.We employed NRK2 knockout (KO) mice to identify the role of NRK-2 in ischemia-induced cardiac remodeling and dysfunction. Following myocardial infarction (MI), or sham surgeries, serial echocardiography was performed in the KO and littermate control mice. Cardiac contractile function rapidly declined and left ventricular interior dimension (LVID) was significantly increased in the ischemic KO vs. control mice at 2 weeks post-MI. An increase in mortality was observed in the KO vs. control group. The KO hearts displayed increased cardiac hypertrophy and heart failure reflected by morphometric analysis. Consistently, histological assessment revealed an extensive and thin scar and dilated LV chamber accompanied with elevated fibrosis in the KOs post-MI. Mechanistically, we observed that loss of NRK-2 enhanced p38α activation following ischemic injury. Consistently, ex vivo studies demonstrated that the gain of NRK-2 function suppresses the p38α as well as fibroblast activation (α-SMA expression) upon TGF-β stimulation, and limits cardiomyocytes death upon hypoxia/re‑oxygenation.Collectively our findings show, for the first time, that NRK-2 plays a critical role in heart failure progression following ischemic injury. NRK-2 deficiency promotes post-MI scar expansion, rapid LV chamber dilatation, cardiac dysfunction and fibrosis possibly due to increased p38α activation.     

The PGC-1α Activator ZLN005 Ameliorates Ischemia-Induced Neuronal Injury In Vitro and In Vivo

Oxidative stress is a great challenge to neurons following cerebral ischemia. PGC-1α has been shown to act as a potent modulator of oxidative metabolism. In this study, the effects of ZLN005, a small molecule that activate PGC-1α, against oxygen–glucose deprivation (OGD)- or ischemia-induced neuronal injury in vitro and in vivo were investigated. Transient middle cerebral artery occlusion (tMCAO) was performed in rats and ZLN005 was administered intravenously at 2 h, 4 h, or 6 h after ischemia onset. Infarct volume and neurological deficit score were detected to evaluate the neuroprotective effects of ZLN005. Well-differentiated PC12 cells, which were subjected to OGD for 2 h followed by reoxygenation for 22 h, were used as an in vitro ischemic model. Changes in expression of PGC-1α, its related genes, and antioxidant genes were determined by real-time quantitative PCR. The results showed that ZLN005 reduced cerebral infarct volume and improved the neurological deficit in rat with tMCAO, and significantly protected OGD-induced neuronal injury in PC12 cells. Furthermore, ZLN005 enhanced expression of PGC-1α in PC12 cells and in the ipsilateral hemisphere of rats with tMCAO. Additionally, ZLN005 increased antioxidant genes, including SOD1 and HO-1, and significantly prevented the ischemia-induced decrease in SOD activity. Taking together, the PGC-1α activator ZLN005 exhibits neuroprotective effects under ischemic conditions and molecular mechanisms possibly involve activation of PGC-1α signaling pathway and cellular antioxidant systems.     

Acute hyperglycaemia enhances oxidative stress and aggravates myocardial ischaemia/reperfusion injury: role of thioredoxin‐interacting protein

Hyperglycaemia during acute myocardial infarction is common and associated with increased mortality. Thioredoxin‐interacting protein (Txnip) is a modulator of cellular redox state and contributes to cell apoptosis. This study aimed to investigate whether or not hyperglycaemia enhances Txnip expression in myocardial ischaemia/reperfusion (MI/R) and consequently exacerbates MI/R injury. Rats were subjected to 30 min. of left coronary artery ligation followed by 4 hrs of reperfusion and treated with saline or high glucose (HG, 500 g/l, 4 ml/kg/h intravenously). In vitro study was performed on cultured rat cardiomyocytes subjected to simulated ischaemia/reperfusion (SI/R) and incubated with HG (25 mM) or normal glucose (5.6 mM) medium. In vivo HG infusion during MI/R significantly impaired cardiac function, aggravated myocardial injury and increased cardiac oxidative stress. Meanwhile, Txnip expression was enhanced whereas thioredoxin activity was inhibited following HG treatment in ischaemia/reperfusion (I/R) hearts. In addition, HG activated p38 MAPK and inhibited Akt in I/R hearts. In cultured cardiomyocytes subjected to SI/R, HG incubation stimulated Txnip expression and reduced thioredoxin activity. Overexpression of Txnip enhanced HG‐induced superoxide generation and aggravated cardiomyocyte apoptosis, whereas Txnip RNAi significantly blunted the deleterious effects of HG. Moreover, inhibition of p38 MAPK or activation of Akt markedly blocked HG‐induced Txnip expression in I/R cardiomyocytes. Most importantly, intramyocardial injection of Txnip siRNA markedly decreased Txnip expression and alleviated MI/R injury in HG‐treated rats. Hyperglycaemia enhances myocardial Txnip expression, possibly through reciprocally modulating p38 MAPK and Akt activation, leading to aggravated oxidative stress and subsequently, amplification of cardiac injury following MI/R.     

Disruption of group IVA cytosolic phospholipase A(2) attenuates myocardial ischemia-reperfusion injury partly through inhibition of TNF-α-mediated pathway

Group IVA cytosolic phospholipase A(2) (cPLA(2)α), which preferentially cleaves arachidonic acid from phospholipids, plays a role in apoptosis and tissue injury. Downstream signals in response to tumor necrosis factor (TNF)-α, a mediator of myocardial ischemia-reperfusion (I/R) injury, involve cPLA(2)α activation. This study examined the potential role of cPLA(2)α and its mechanistic link with TNF-α in myocardial I/R injury using cPLA(2)α knockout (cPLA(2)α(-/-)) mice. Myocardial I/R was created with 10-wk-old male mice by 1 h ligation of the left anterior descending coronary artery, followed by 24 h of reperfusion. As a result, compared with wild-type (cPLA(2)α(+/+)) mice, cPLA(2)α(-/-) mice had a 47% decrease in myocardial infarct size, preservation of echocardiographic left ventricle (LV) function (%fractional shortening: 14 vs. 21%, respectively), and lower content of leukotriene B(4) and thromboxane B(2) (62 and 50% lower, respectively) in the ischemic myocardium after I/R. Treatment with the TNF-α inhibitor (soluble TNF receptor II/IgG1 Fc fusion protein, sTNFR:Fc) decreased myocardial I/R injury and LV dysfunction in cPLA(2)α(+/+) mice but not cPLA(2)α(-/-) mice. sTNFR:Fc also suppressed cPLA(2)α phosphorylation in the ischemic myocardium after I/R of cPLA(2)α(+/+) mice. Similarly, sTNFR:Fc exerted protective effects against hypoxia-reoxygenation (H/R)-induced injury in the cultured cardiomyocytes from cPLA(2)α(+/+) mice but not cPLA(2)α(-/-) cardiomyocytes. H/R and TNF-α induced cPLA(2)α phosphorylation in cPLA(2)α(+/+) cardiomyocytes, which was reversible by sTNFR:Fc. In cPLA(2)α(-/-) cardiomyocytes, TNF-α induced apoptosis and release of arachidonic acid to a lesser extent than in cPLA(2)α(+/+) cardiomyocytes. In conclusion, disruption of cPLA(2)α attenuates myocardial I/R injury partly through inhibition of TNF-α-mediated pathways.     

Epoxyeicosatrienoic acids protect rat hearts against tumor necrosis factor-α-induced injury

Epoxyeicosatrienoic acids (EET), the primary arachidonic acid metabolites of cytochrome P450 2J (CYP2J) epoxygenases, possess potent vasodilatory, anti-inflammatory, antiapoptotic, and mitogenic effects. To date, little is known about the role of CYP2J2 and EETs in tumor necrosis factor (TNF)-α-induced cardiac injury. We utilized cell culture and in vivo models to examine the effects of exogenously applied EETs or CYP2J2 overexpression on TNF-α-induced cardiac apoptosis and cardiac dysfunction. In neonatal rat cardiomyocytes, TNF-α-induced apoptosis was markedly attenuated by EETs or CYP2J2 overexpression, leading to significantly improved cell survival. Further studies showed that TNF-α decreased expression of the antiapoptotic proteins Bcl-2 and Bcl-xL, decreased IκBα and PPARγ, and also inhibited PI3K-dependent Akt and EGFR signaling. Both EETs and CYP2J2 overexpression reversed the effects of TNF-α on these pathways. Furthermore, overexpression of CYP2J2 in rats prevented the decline in cardiac function that is normally observed in TNF-α-challenged animals. These results demonstrate that EETs or CYP2J2 overexpression can prevent TNF-α-induced cardiac cell injury and cardiac dysfunction by inhibiting apoptosis, reducing inflammation, and enhancing PPARγ expression. Targeting the CYP2J2 epoxygenase pathway may represent a novel approach to mitigate cardiac injury in diseases such as heart failure, where increased TNF-α levels are known to occur.     

Gene 33/RALT is induced by hypoxia in cardiomyocytes, where it promotes cell death by suppressing phosphatidylinositol 3-kinase and extracellular signal-regulated kinase survival signaling

Ischemia in the heart deprives cardiomyocytes of oxygen, triggering cell death (myocardial infarction). Ischemia and its cell culture model, hypoxia, elicit a stress response program that contributes to cardiomyocyte death; however, the molecular components required to promote this process remain nebulous. Gene 33 is a 50-kDa cytosolic adapter protein that suppresses signaling from receptor Tyr kinases of the epidermal growth factor receptor/ErbB family. Here we show that adenoviral expression of Gene 33 swiftly stimulates cardiomyocyte death coincident with reduced Akt and extracellular signal-regulated kinase (ERK) signaling. Subjecting cardiomyocytes to hypoxia and then reoxygenation induces gene 33 mRNA and Gene 33 protein. RNA interference experiments indicate that endogenous Gene 33 reduces Akt and ERK signaling and is required for maximal hypoxia-induced cardiomyocyte death. Gene 33 levels are also strikingly increased in myocardial ischemic injury and infarction. Our results identify a new role for Gene 33 as a component in the molecular pathophysiology of ischemic injury.     

AGGF1 protects from myocardial ischemia/reperfusion injury by regulating myocardial apoptosis and angiogenesis

Angiogenic factor with G patch and FHA domains 1 (AGGF1) is a newly identified proangiogenic protein, which plays an important role in vascular disease and angiogenesis. However, its role in myocardial ischemia/reperfusion (I/R) injury remains unknown. This study investigated whether AGGF1 is involved in the pathogenesis of mouse myocardial I/R injury and the underlying mechanisms. Wild-type (WT) C57BL/6 J mice were treated at 30 min prior to I/R injury with anti-AGGF1 neutralizing antibody (3 mg/kg) or recombinant human AGGF1 (rhAGGF1, 0.25 mg/kg). After I/R injury, the infarct size, the number of TUNEL-positive cardiomyocytes, Bax/Bcl2 ratio, inflammatory cytokine expression and angiogenesis were markedly increased as compared with sham control. Treatment of WT mice with anti-AGGF1 neutralizing antibody resulted in exaggeration of myocardial I/R injury but reducing angiogenesis. In contrast, administration of rhAGGF1 markedly reversed these effects. Furthermore, anti-AGGF1- or rhAGGF1-mediated effects on I/R-induced cardiac apoptosis, inflammation and angiogenesis were dose dependent. In addition, the protective effects of AGGF1 on cardiomyocyte apoptosis and inflammation were confirmed in cultured cardiomyocytes after I/R. Finally, these effects were associated with activation of ERK1/2, Stat3 and HIF-1α/VEGF pathways and inhibition of activation of NF-κB, p53 and JNK1/2 pathways. In conclusion, we report the first in vivo and in vitro evidence that AGGF1 reduces myocardial apoptosis and inflammation and enhances angiogenesis, leading to decreased infarct size after I/R injury. These results may provide a novel therapeutic approach for ischemic heart diseases.     

The cardioprotective effect of dihydromyricetin prevents ischemia–reperfusion-induced apoptosis in vivo and in vitro via the PI3K/Akt and HIF-1α signaling pathways

Reperfusion therapy is widely used to treat acute myocardial infarction (AMI). However, further injury to the heart induced by rapidly initiating reperfusion is often encountered in clinical practice. A lack of pharmacological strategies in clinics limits the prognosis of patients with myocardial ischemia-reperfusion injury (MIRI). Dihydromyricetin (DMY) is one of the most abundant components in vine tea, commonly known as the tender stems and leaves of Ampelopsis grossedentata. The aim of this study was to evaluate the cardioprotection of DMY against myocardial ischemia-reperfusion (I/R) injury and to further investigate the underlying mechanism. An I/R injury was induced by left anterior descending coronary artery occlusion in adult male rats in vivo and a hypoxia–reoxygenation (H/R) injury in H9c2 cardiomyocytes in vitro. We found that DMY pretreatment provided significant protection against I/R-induced injury, including enhanced antioxidant capacity and inhibited apoptosis in vivo and in vitro. This effect correlated with the activation of the PI3K/Akt and HIF-1α signaling pathways. Conversely, blocking Akt activation with the PI3K inhibitor LY294002 effectively suppressed the protective effects of DMY against I/R-induced injury. In addition, the PI3K inhibitor partially blocked the effects of DMY on the upregulation of Bcl-2, Bcl-xl, procaspase-3, -8, and -9 protein expression and the downregulation of HIF-1α, Bnip3, Bax, Cyt-c, cleaved caspase-3, -8, and -9 protein expression. Collectively, these results showed that DMY decreased the apoptosis and necrosis by I/R treatment, and PI3K/Akt and HIF-1α plays a crucial role in protection during this process. These observations indicate that DMY has the potential to exert cardioprotective effects against I/R injury and the results might be important for the clinical efficacy of AMI treatment.     

ΔNp63α regulates keratinocyte proliferation by controlling PTEN expression and localization

ΔNp63α, implicated as an oncogene, is upregulated by activated Akt, part of a well-known cell survival pathway. Inhibition of Akt activation by phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and the presence of putative p63-binding sites in the pten promoter led us to investigate whether ΔNp63α regulates PTEN expression. Knockdown of ΔNp63α led to increases in PTEN levels and loss of activated Akt, while overexpression of ΔNp63α decreased PTEN levels and elevated active Akt. The repression of PTEN by ΔNp63α occurs independently of p53 status, as loss of ΔNp63α increases PTEN expression in cell lines with and without functional p53. In addition, decreased levels of ΔNp63α resulted in an increase in nuclear PTEN. Conversely, in vivo nuclear PTEN was absent in the proliferative basal layer of the epidermis where ΔNp63α expression is highest. Additionally, we show that in keratinocytes a balance between ΔNp63α and PTEN regulates Akt activation and maintains normal proliferation rates. This balance is disrupted in non-melanoma skin cancers through increased ΔNp63α levels, and could enhance proliferation and subsequent neoplastic development. Our studies show that ΔNp63α negatively regulates PTEN, thereby providing a feedback loop between PTEN, Akt and ΔNp63α, which has an integral role in skin cancer development.     

Reduction of SIRT1 blunts the protective effects of ischemic post-conditioning in diabetic mice by impairing the Akt signaling pathway

Ischemic post-conditioning (IPO) activates Akt signaling to confer cardioprotection. The responsiveness of diabetic hearts to IPO is impaired. We hypothesized that decreased cardiac SIRT1, a positive regulator of Akt, may be responsible for the impaired responsiveness of diabetic hearts to IPO-mediated cardioprotection. High-fat diet and streptozotocin-induced diabetic mice were subjected to myocardial ischemia/reperfusion (MI/R, 30 min ischemia and 180 min reperfusion) or IPO (three cycles of 10 s of reperfusion and ischemia at the onset of reperfusion). Adenoviral vectors encoding GFP or SIRT1 (Ad-SIRT1) were administered by direct injection into the left ventricular. Our results showed that IPO activated the Akt signaling pathway and reduced MI/R injury in non-diabetic hearts but not in diabetic hearts, in which reduced expression of SIRT1 and increased Akt acetylation were observed. Delivery of Ad-SIRT1 into the diabetic hearts reduced Akt acetylation and restored the cardioprotective effects of IPO by modulating Akt signaling pathway. In contrast, cardiac-specific SIRT1 knockout increased Akt acetylation and blunted the cardioprotective effects of IPO. In in vitro study, transfection with wild-type SIRT1 but not inactive mutant SIRT1 reduced the expression of Akt acetylation and restored the protective effects of hypoxic post-conditioning in high glucose-incubated cardiomyocytes. Moreover, the cardiomyocytes transfected with constitutive Akt acetylation showed repressed Akt phosphorylation and blunted protective effects against hypoxia/reoxygenation injury. These findings demonstrate that the reduction of SIRT1 blunts the protective effects of IPO by impairing Akt signaling pathway and that SIRT1 up-regulation restores IPO-mediated cardioprotection in diabetic mice via deacetylation-dependent activation of Akt signaling pathway.     

Tetramethylpyrazine Protects Against Early Brain Injury and Inhibits the PERK/Akt Pathway in a Rat Model of Subarachnoid Hemorrhage

Neuronal apoptosis is a potentially fatal pathological process that occurs in early brain injury (EBI) after subarachnoid hemorrhage (SAH). There is an urgent need to identify effective therapeutics to alleviate neuronal apoptosis. Tetramethylpyrazine (TMP), as an important component of the Chinese traditional medicinal herb Ligusticum wallichii, has been widely used in China to treat cerebral ischemic injury and confer neuroprotection. In the present work, we investigate whether TMP can reduce EBI following SAH in rats, specifically via inactivating the PERK/Akt signaling cascade. One hundred twenty-five male Sprague–Dawley rats were used in the present study. TMP was administered by intravenous (i.v.) injection, and the Akt inhibitor MK2206 was injected intracerebroventricularly (i.c.v.). SAH grade, neurological scores, and brain water content were measured 24 h after SAH. Neuronal apoptosis was visualized by Fluoro-Jade C (FJC) staining. Western blotting was used to measure the levels of PERK, p-PERK, eIF2α, p-eIF2α, Akt, p-Akt, Bcl-2, Bax, and cleaved caspase-3. Our results showed that TMP effectively reduced neuronal apoptosis and improved neurobehavioral deficits 24 h after SAH. Administration of TMP reduced the abundance of p-PERK and p-eIF2α. In addition, TMP increased the p-Akt level and the Bcl-2/Bax ratio and decreased the level of cleaved caspase-3. The selective Akt inhibitor MK2206 abolished the anti-apoptotic effect of TMP at 24 h after SAH. Collectively, these results indicate that Akt-related anti-apoptosis through the PERK pathway is a major, potent mechanism of EBI. Further investigation of this pathway may provide a basis for the development of TMP as a clinical treatment.     

Up-regulation of orphan nuclear estrogen-related receptor alpha expression during long-term caloric restriction in mice

The estrogen-related receptor alpha (ERRα) is an orphan receptor belonging to the nuclear receptor superfamily that regulates a number of target genes encoding enzymes that participate in various metabolic pathways involved in maintaining energy balance in animals. In this study, whether long-term caloric restriction (alternate days of fasting for 3 months) in mice modulates the expression of ERRα in various tissues was investigated. Western blot analyses showed positive immunoreactive ERRα protein (53 kDa) band in various mice tissue extracts, though at varying levels. Heart, kidney, and skeletal muscles expressed significant levels of ERRα, with a comparatively lower level detected in the intestine, brain, and liver. Cardiac ERRα expression was the highest, with the least detected in the liver. Caloric restricted mice exhibited a significant increase in ERRα level in the heart (5.45-fold), kidney (3.70-fold), skeletal muscle (3.0-fold), small intestine (2.72-fold), and liver (2.44-fold) extracts as compared to ad libitum fed. However, caloric restriction could not evoke any detectable receptor level change in the brain. Notably, the highest ERRα up-regulation was detected in the heart. This up-regulation in ERRα level especially in highly oxidative tissues such as heart, kidney, small intestine, and skeletal muscle of caloric restricted mice may be helpful in modulating ERRα responsive genes that participates in maintaining energy balance. This may potentially strengthen the metabolic and biochemical adaptation in such tissues, which is necessary for animal survival under long-term caloric restriction.     

SDF-1 induces TNF-mediated apoptosis in cardiac myocytes

Chemokines are small secreted proteins with chemoattractant properties that play a key role in inflammation. One such chemokine, Stromal cell-derived factor-1 (SDF-1) also known as CXCL12, and its receptor, CXCR4, are expressed and functional in cardiac myocytes. SDF-1 both stimulates and enhances the cellular signal which attracts potentially beneficial stem cells for tissue repair within the ischemic heart. Paradoxically however, this chemokine is known to act in concert with the inflammatory cytokines of the innate immune response which contributes to cellular injury through the recruitment of inflammatory cells during ischemia. In the present study, we have demonstrated that SDF-1 has dose dependent effects on freshly isolated cardiomyocytes. Using Tunnel and caspase 3-activation assays, we have demonstrated that the treatment of isolated adult rat cardiac myocyte with SDF-1 at higher concentrations (pathological concentrations) induced apoptosis. Furthermore, ELISA data demonstrated that the treatment of isolated adult rat cardiac myocyte with SDF-1 at higher concentrations upregulated TNF-α protein expression which directly correlated with subsequent apoptosis. There was a significant reduction in SDF-1 mediated apoptosis when TNF-α expression was neutralized which suggests that SDF-1 mediated apoptosis is TNF-α-dependent. The fact that certain stimuli are capable of driving cardiomyocytes into apoptosis indicates that these cells are susceptible to clinically relevant apoptotic triggers. Our findings suggest that the elevated SDF-1 levels seen in a variety of clinical conditions, including ischemic myocardial infarction, may either directly or indirectly contribute to cardiac cell death via a TNF-α mediated pathway. This highlights the importance of this receptor/ligand in regulating the cardiomyocyte response to stress conditions.     

Inhibition of miR-181b-5p protects cardiomyocytes against ischemia/reperfusion injury by targeting AKT3 and PI3KR3

Ischemic heart disease (IHD) is the most occurring cardiovascular-associated disease, which is a primary leading cause of cardiac disability and death worldwide. Myocardial ischemia/reperfusion injury (MI/RI) has been linked to IHD-induced cardiomyocytes apoptosis and tissue damage. The clinical studies have indicated that pathophysiologic mechanisms of MI/RI are associated with reactive oxygen species generation, calcium overload, energy metabolism disorder, neutrophil infiltration, and others. However, the genetic mechanism of MI/RI remains unclear. In this study, we successfully established the reproducing abnormal heart observed in rat, of IHD-induced MI/RI post operation. By using these rats, we illustrated that expression of miR-181b-5p was increased not only in both hypoxia/reoxygenation-cultured H9C2 but also heart of myocardial ischemia/reperfusion (MI/R) rat. Suppression of the miR-181b-5p cardiomyocytes apoptosis and rescued myocardial infarction. Additionally, our data indicated that miR-181b-5p negatively regulates the expression of AKT3 and PIK3R3 through directly binding with its 3′-untranslated region. More importantly, suppression of miR-181b-5p protects the cardiomyocytes apoptosis and tissue damage from MI/R via regulation of PIK3R3 and AKT3. Hence, our study indicates that miR-181b-5p is essential for MI/RI via regulation of PI3K/Akt signaling pathway and could be a potential therapeutic target in IHD.     

The circadian nuclear receptor RORα negatively regulates cerebral ischemia–reperfusion injury and mediates the neuroprotective effects of melatonin

Disruptions of the circadian rhythm and reduced circulating levels of the circadian hormone melatonin predispose to ischemic stroke. Although the nuclear receptor RORα is considered as a circadian rhythm regulator and a mediator of certain melatonin effects, its potential role in cerebral ischemia-reperfusion (CI/R) injury and in the neuroprotective effects of melatonin remain undefined. Here, we observed that CI/R injury in RORα-deficient mice was associated with greater cerebral infarct size, brain edema, and cerebral apoptosis compared with wild-type model. In contrast, transgenic mice with brain-specific overexpression of RORα versus non-transgenic controls exerted significantly reduced infarct volume, brain edema and apoptotic response induced by CI/R. Mechanistically, RORα deficiency was found to exacerbate apoptosis pathways mediated by endoplasmic-reticulum stress and mitochondria and aggravate oxidative/nitrative stress after CI/R. Further studies revealed that RORα deficiency intensified the activation of nuclear factor-κB signaling induced by CI/R. Given the emerging evidence of RORα as an essential melatonin activity mediator, we further investigated the RORα roles in melatonin-exerted neuroprotection against acute ischemic stroke. Melatonin treatment significantly decreased infarct volume and cerebral apoptosis; mitigated endoplasmic reticulum stress and mitochondrial dysfunction; and inhibited CI/R injury-induced oxidative/nitrative stress and nuclear factor-κB activation, which was eradicated in RORα-deficient mice. Collectively, current findings suggest that RORα is a novel endogenous neuroprotective receptor, and a pivotal mediator of melatonin's suppressive effects against CI/R injury.     

Sensory–sympathetic coupling in superior cervical ganglia after myocardial ischemic injury facilitates sympathoexcitatory action via P2X7 receptor

P2X receptors participate in cardiovascular regulation and disease. After myocardial ischemic injury, sensory–sympathetic coupling between rat cervical DRG nerves and superior cervical ganglia (SCG) facilitated sympathoexcitatory action via P2X₇ receptor. The results showed that after myocardial ischemic injury, the systolic blood pressure, heart rate, serum cardiac enzymes, IL-6, and TNF-α were increased, while the levels of P2X₇ mRNA and protein in SCG were also upregulated. However, these alterations diminished after treatment of myocardial ischemic (MI) rats with the P2X₇ antagonist oxATP. After siRNA P2X₇ in MI rats, the systolic blood pressure, heart rate, serum cardiac enzymes, the expression levels of the satellite glial cell (SGC) or P2X₇ were significantly lower than those in MI group. The phosphorylation of ERK 1/2 in SCG participated in the molecular mechanism of the sympathoexcitatory action induced by the myocardial ischemic injury. Retrograde tracing test revealed the sprouting of CGRP or SP sensory nerves (the markers of sensory afferent fibers) from DRG to SCG neurons. The upregulated P2X₇ receptor promoted the activation of SGCs in SCG, resulting in the formation of sensory–sympathetic coupling which facilitated the sympathoexcitatory action. P2X₇ antagonist oxATP could inhibit the activation of SGCs and interrupt the formation of sensory–sympathetic coupling in SCG after the myocardial ischemic injury. Our findings may benefit the treatment of coronary heart disease and other cardiovascular diseases.     

Effects of pre-germinated brown rice treatment high-fat diet-induced metabolic syndrome in C57BL/6J mice

To investigate using pre-germinated brown rice (PGBR) to treat metabolic syndrome, we fed one group of mice standard-regular-diet (SRD) for 20 weeks and another group of mice high-fat-diet (HFD) for 16 weeks. We subdivided them into HFD group and HFD + PGBR group whose dietary carbohydrate was replaced with PGBR for 4 weeks. The HFD group gained more weight, had higher blood pressure, heart rate, blood glucose and lipids, liver levels of TG, feces TG and bile acid, lower adipose levels of adipocytokine, lower skeletal muscle IR, IRS-1, IRS-2, PI3 K, Akt/PKB, GLUT-1, GLUT-4, GCK and PPAR-γ; higher liver SREBP-1, SCD-1, FAS, HMGCR, LDLR, CYP7α1 and PPAR-α, and higher adipose SREBP-1, SCD-1, FAS, and lower adipose PPAR-α and adiponectin. The HFD + PGBR group had clearly improved blood pressure, biochemical parameters and above proteins expressions. PGBR successful treatment of metabolic syndrome was achieved through improvements in glucose and lipid synthesis and metabolism.