Elevation Of Tumor Necrosis Factor-α Research Articles

Effect of Metformin on Myocardial Injury Induced by Hepatic Ischemia-Reperfusion in Rats.

Background: There is no effective medication for treatment or prevention of hepatic ischemia-reperfusion (HIR) injury caused by liver transplantation and hepatectomy. This study aimed to investigate the therapeutic effects of metformin on HIR injury and related myocardial injury in rats. Methods: Wistar male rats were randomly divided into four groups: sham group, ischemia-reperfusion group, and IR group treated with metformin 150 mg/kg and 100 mg/kg. Wistar male rats were administered metformin 150 mg/kg, 100 mg/kg or saline 30 min pre-operative and underwent 15 min ischemia and 6 h reperfusion (n = 4). Results: Metformin significantly alleviates the injury caused by HIR. Administration of metformin resulted in a significant reduction in the serum levels of alanine transaminase and aspartate transaminase and the activity of malondialdehyde, creatine kinase-MB, and lactate dehydrogenase but maintained high catalase and superoxide dismutase activity. Metformin significantly inhibited the IR-induced elevation of tumor necrosis factor-α in liver and heart tissue. Conclusion: Metformin can alleviate hepatic and myocardial injury induced by IR by inhibiting oxidative stress.

Effect of parthenolide, an NLRP3 inflammasome inhibitor, on insulin resistance in high-fat diet-obese mice.

The activation of Nod-like receptor proteins (NLRP3) containing the pyrin domain inflammasome is a hallmark of the pathogenesis of metabolic disorders. Inhibition of the NLRP3 inflammasome by phytoconstituents has been attempted as a strategy to mitigate these disorders. Therefore, the present study aimed to evaluate the efficacy of an NLRP3 inflammasome inhibitor, parthenolide (PN; 5mg/kg i.p.) against inflammation and insulin resistance in high-fat diet (HFD) - obese mice. Treatment with PN and pioglitazone (PIO; 30mg/kg p.o.) attenuated lipopolysaccharide (LPS; 1 ng/ml) - induced elevation of tumor necrosis factor-α and interleukin-1β in mouse peritoneal macrophages in a dose-dependent manner. Sixty days of PN and PIO treatment marginally reduced obesity-induced insulin resistance in HFD-obese mice. PN treatment also decreased blood glucose from 14th to 60th day, supporting the hypothesis of simultaneous attenuation of inflammation and insulin resistance in obese mice. Thus, PN treatment was also evident with significant improvement in glucose tolerance and peripheral insulin resistance validated through the respective tolerance tests. Therefore, the present study suggests that PN, an NLRP3 inflammasome inhibitor, could be a possible therapeutic agent for attenuating obesity-induced insulin resistance.

Chrysin promotes attenuation of depressive-like behavior and hippocampal dysfunction resulting from olfactory bulbectomy in mice

Chrysin is a natural flavonoid which is found in bee propolis, honey and various plants, and antidepressant-like effect of chrysin in chronically stressed mice was previously demonstrated by our group. In this work, we investigated the action of chrysin treatment (5 or 20 mg/kg) for 14 days in the depressant-like behavior and in the hippocampal dysfunction induced by olfactory bulbectomy (OB), an animal model of agitated depression. Results demonstrated that OB occasioned a depressant-like behavior in the splash test, open field test and forced swimming test. Chrysin administration, similarly to fluoxetine (positive control), promoted the attenuation of these behavioral modifications. OB also caused the elevation of tumor necrosis factor-α, interferon-γ, interleukin-1β, interleukin-6, kynurenine (KYN) levels and indoleamine-2,3-dioxygenase activity, as well as occasioned the decrease of 5-hydroxytryptamine (5-HT) and brain-derived neurotrophic factor (BDNF) levels and increase KYN/tryptophan and 5-hydroxyindoleacetic acid/5-HT ratio in the hippocampus. Chrysin therapy prevented against all these alterations in the hippocampus. In addition, chrysin treatment (20 mg/kg) resulted in the up-regulation of BDNF levels in the control animals, reinforcing our hypothesis that up-regulation of BDNF synthesis play a key role in the antidepressant action of chrysin. In conclusion, this study showed that chrysin, similarly to fluoxetine, is capable of promoting the attenuation of depressant-like behavior and hippocampal dysfunction resulting from OB in mice. These results reinforced the potential of chrysin for the treatment or supplementary treatment of depression, as well as showed that chrysin is also effective with 14 days of therapy in a model of agitated depression.

Chronic Elevation of Tumor Necrosis Factor-α Mediates the Impairment of Leptomeningeal Arteriogenesis in db/db Mice.

Leptomeningeal collateral growth is a key factor that defines the severity of ischemic stroke. Patients with stroke generally have vascular risk factors, such as diabetes mellitus; however, consensus is lacking on how diabetes mellitus affects leptomeningeal arteriogenesis. We investigate the influence of diabetes mellitus on the leptomeningeal arteriogenesis. We measured the vessel diameter of the leptomeningeal anastomoses 14 days after the common carotid artery occlusion in db/db, db/+, and streptozotocin-induced hyperglycemic mice. In another set of these mice, we measured the infarct volume attributed to subsequent middle cerebral artery occlusion 14 days after the common carotid artery occlusion. Mac-2-positive cells on the dorsal brain surface and the mRNA expression of several macrophage-related factors in the cerebral cortex were examined. Finally, we tested whether the leptomeningeal arteriogenesis could be restored by pharmaceutical intervention in the db/db mice. Cerebral hypoperfusion led to significant ipsilateral leptomeningeal collateral growth in db/+ mice and streptozotocin-induced hyperglycemic mice. The collateral growth contributed to reduced infarct volume. In contrast, leptomeningeal arteriogenesis was impaired in the db/db mice. The number of Mac-2-positive cells was increased and tumor necrosis factor-α mRNA expression was induced after common carotid artery occlusion in the db/+ mice. However, these responses were not observed in the db/db mice. Administration of the tumor necrosis factor-α inhibitor etanercept before common carotid artery occlusion restored the hypoperfusion-induced leptomeningeal collateral growth in db/db mice. These results indicate that leptomeningeal arteriogenesis is impaired in db/db mice and that suppression of the tumor necrosis factor-α response to hypoperfusion is the major contributing factor.

Decaffeinated coffee prevents scopolamine-induced memory impairment in rats

IntroductionSeveral human studies have reported that coffee consumption improves cognitive performance. In the present study, we investigated whether instant decaffeinated coffee also ameliorates cognitive performance and attenuates the detrimental effects of scopolamine on memory. MethodsMemory performance was evaluated in Morris water maze test and passive avoidance test. Instant decaffeinated coffee (p.o.) at 120 or 240mg/kg in Sprague-Dawley rats, which is equivalent to approximately three or six cups of coffee, respectively, in a 60kg human, was administered for two weeks. ResultsOral gavage administration of instant decaffeinated coffee inhibited scopolamine-induced memory impairment, which was measured by Morris water maze test and passive avoidance test. Instant decaffeinated coffee suppressed scopolamine-mediated elevation of tumor necrosis factor-α (TNF-α) and stimulation of nuclear factor-κB (NF-κB) pathway (i.e., phosphorylation of IκBα and p65) in the rat hippocampus. DiscussionThese findings suggest that caffeine-free decaffeinated coffee may prevent memory impairment in human through the inhibition of NF-κB activation and subsequent TNF-α production.

Elevation of tumor necrosis factor-α, interleukin-1β and interleukin-6 levels in aortic intima of Chinese Guizhou minipigs with streptozotocin-induced diabetes

Large animal models with toxin-mediated pancreatic damage have been used extensively in researches with respect to diabetes mellitus and cardiovascular diabetic complications. The present study aimed to establish Chinese Guizhou minipig models with streptozotocin (STZ)-induced diabetes and characterize the animal models by analyzing inflammatory cytokine levels in aortic wall, such as tumor necrosis factor (TNF)-alpha, interleukin-1beta (IL-1beta) and interleukin-6 (IL-6). Twenty-two male Chinese Guizhou minipigs (age, 4 to 6 months; weight, 20 kg to 30 kg) were divided into STZ-induced diabetic group (n = 12) and control group (n = 10). STZ (125 mg/kg) was administrated to induce hyperglycemia and afterwards insulin was used to control fasting blood glucose levels below 10 mmol/L. Oral glucose tolerance test (OGTT) was performed before and one month after STZ administration and serum concentrations of alanine transaminase, asparagine transaminase, albumin, blood urea nitrogen, creatinine, lipids and white blood cell count were measured before and six months later. Animals in both groups were euthanized after six months and pancreas was examined immunohistochemically for islet beta cells. Aortic intima of diabetic minipigs and controls was analyzed for TNF-alpha level in tissue conditioned medium by Western blot. TNF-alpha, IL-1beta and IL-6 mRNA levels in aortic intima were assayed by reverse transcription and polymerase chain reaction (RT-PCR). Significant elevation in serum glucose levels was observed one month and six months after STZ induction (P < 0.001) and markedly increased OGTT values were noted, compared with baseline data. The normal pancreas had many irregular sized islets and small clusters of islet beta cells, while in pancreas of diabetic minipigs islet beta cells almost disappeared. No statistical difference was notified in serum concentrations of biochemical examinations before and six months after STZ induction. Western blot demonstrated dramatically increased TNF-alpha level in aotic intima conditioned medium, and significant elevation of TNF-alpha, IL-1beta and IL-6 mRNA levels was revealed by RT-PCR. The present study has established Chinese Guizhou minipig models with STZ-induced diabetes. Inflammatory cytokines (TNF-alpha, IL-1beta and IL-6) significantly elevated in aortic intima of diabetic minipigs.

Elevation of tumor necrosis factor-alpha and increased risk of recurrent coronary events after myocardial infarction.

Levels of tumor necrosis factor-alpha (TNF-alpha) increase with acute ischemia. However, whether elevations of TNF-alpha in the stable phase after myocardial ischemia (MI) are associated with increased risk of recurrent coronary events is unknown. A nested case-control design was used to compare TNF-alpha levels obtained an average of 8.9 months after initial MI among 272 participants in the Cholesterol And Recurrent Events (CARE) trial who subsequently developed recurrent nonfatal MI or a fatal cardiovascular event (cases) and from an equal number of age- and sex-matched participants who remained free of these events during follow-up (controls). Overall, TNF-alpha levels were significantly higher among cases than controls (2.84 versus 2.57 pg/mL, P=0.02). The excess risk of recurrent coronary events after MI was predominantly seen among those with the highest levels of TNF-alpha, such that those with levels in excess of 4.17 pg/mL (the 95th percentile of the control distribution) had an approximately 3-fold increase in risk (RR=2.7, 95% CI 1.4 to 5.2, P=0.004). Risk estimates were independent of other risk factors and were similar in subgroup analyses limited to cardiovascular death (RR=2.1) or to recurrent nonfatal MI (RR=3.2). Plasma concentrations of TNF-alpha are persistently elevated among post-MI patients at increased risk for recurrent coronary events. These data support the hypothesis that a persistent inflammatory instability is present among stable patients at increased vascular risk. Novel therapies designed to attenuate inflammation may thus represent a new direction in the treatment of MI.

Interleukin 1 and Tumor Necrosis Factor Production as the Initial Stimulants of Liver Ischemia and Reperfusion Injury

The mechanisms by which polymorphonuclear neutrophils (PMNs) are recruited by the ischemic and reperfused liver are still unknown. The purpose of this study was to determine whether tumor necrosis factor-α (TNF) and/or interleukin-1α (IL-1) acted as potential mediators for PMN infiltration after liver ischemia and reperfusion. The potential effect of FK 506, a powerful immunosuppressant, was also studied. Male Sprague-Dawley rats were subjected to 60 and 90 min of total hepatic ischemia, with an extracorporeal portosystemic shunt. FK 506 (0.3 mg/kg) was intravenously administered 4 hr before ischemia (FK 506 group), and control animals received normal saline solution (NS group). Plasma TNF, IL-1 levels, and PMN infiltration in liver tissue were serially examined at the end of ischemia, 5, 30, 60, and 360 min after reperfusion. The degree of liver necrosis was assessed at 360 min following reperfusion. In the NS group, IL-1 and TNF revealed a transient elevation at 30 and 60 min after reperfusion, following 60 min of ischemia. When the ischemia was increased to 90 min, the IL-1 activity had a rapid elevation (330.5 ± 129 pg/ml) at 5 min, which remained at high levels (197.8 ± 70.4 pg/ml) until 6 hr after reperfusion, whereas the TNF activity decreased to normal levels following a similar peak (355 ± 181.9 pg/ml) at 5 min after reperfusion. The time course of IL-1 release in the NS group, with 90 min of ischemia, correlated directly with the PMN infiltration. Irrespective of the ischemic period, the FK 506 group inhibited the elevation of TNF and IL-1 levels, which resulted in amelioration of PMN infiltration and hepatic lesion. It appears then that IL-1, rather than TNF, acted as a continuous stimulant for PMN infiltration following severe liver ischemia and reperfusion.