Action Of Tempol Research Articles

Tempol differential effect on prostate cancer inflammation: In vitro and in vivo evaluation.

Tempol is a redox-cycling nitroxide that acts directly on inflammation. However, few studies have reported the use of tempol in prostate cancer (PCa). The present study investigated the effects of tempol on inflammation related to NF-κB signaling, using hormone-dependent or hormone-independent cell lines and the transgenic adenocarcinoma of the mouse prostate PCa animal model in the early and late stages of cancer progression. PC-3 and LnCaP cells were exposed to different tempol doses in vitro, and cell viability assays were performed. The optimal treatment dose was chosen for subsequent analysis using western blotting. Fiveexperimental groups were evaluated in vivo to test for tempol effects in the early (CT12 and TPL12 groups) and late stages (CT20, TPL20-I, and TLP20-II) of PCa development. The TPL groups were treated with 50 or 100 mg/kg tempol. All control groups received water as the vehicle. The ventral lobe of the prostate was collected and subjected to immunohistochemical and western blotanalysis. Tempol treatment reduced cellular proliferation in vitro and improved prostatic morphology in vivo, thereby decreasing tumor progression. Tempol reduced inflammation in preclinical models, and downregulated the initial inflammatory signaling through toll-like receptors, not always mediated by the MyD88 pathway. In addition, it upregulated iκB-α and iκB -β levels, leading to a decrease in NF-κB, TNF-α, and other inflammatory markers. Tempol also influenced cell survival markers. Tempol can be considered a beneficial therapy for PCa treatment owing to its anti-inflammatory and antiproliferative effects. Nevertheless, the action of tempol was different depending on the degree of the prostatic lesion in vivo and hormone reliance in vitro. This indicates that tempol plays a multifaceted role in the prostatic tissue environment.

Tempol (4-hydroxy tempo) protects mice from cisplatin-induced acute kidney injury via modulation of expression of aquaporins and kidney injury molecule-1

Tempol (4-hydroxy tempo), a pleiotropic antioxidant is reported to afford protection against cisplatin (CP)-induced nephrotoxicity. However, molecular mechanisms of action of tempol in improving the renal function in CP-induced nephrotoxicity are not fully understood. We investigated the attenuating effect of tempol against CP-induced alterations in kidney injury molecule-1 (KIM-1) and aquaporins (AQPs) in mice. Tempol (100 mg/kg, po) pretreatment with CP (20 mg/kg ip) showed restoration in renal function markers including electrolytes. CP treatment upregulated mRNA expression of KIM-1 and downregulated AQP and arginine vasopressin (AVP) expression which was attenuated by tempol. Immunoblotting analysis revealed that CP-induced alterations in KIM-1 and AQP expression were restored by tempol. Immunofluorocense study also showed restorative effect of tempol on the expression of AQP2 in CP-treated mice. In conclusion, this study provides experimental evidence that tempol resolved urinary concentration defect by the restoration of AQP, AVP and KIM-1 levels indicating a potential use of tempol in ameliorating the AKI in cancer patients under the treatment with CP.

Nitroxide 4-hydroxy-2,2′,6,6′-tetramethylpiperidine 1-oxyl (Tempol) inhibits the reductase activity of protein disulfide isomerase via covalent binding to the Cys400 residue on CXXC redox motif at the a′active site

Background and aimOxidative stress arising from inflammatory processes is a serious cause of cell and tissue damage. Tempol is an efficient antioxidant with superoxide dismutase-like activity. The purpose of this paper is to address the inhibition of protein disulfide isomerase (PDI), an essential redox chaperone whose active sites contain the Cys-Gly-His-Cys (CXXC) motif, by the nitroxide Tempol. ResultsIn the presence of Tempol (5–120 μM), the reductase activity of PDI was reversibly affected both in vitro and in activated mice neutrophils, with an IC50 of 22.9 ± 10.8 μM. Inhibitory activity was confirmed by using both the insulin method and fluorescent formation of eosin-glutathione (E-GSH). The capacity of Tempol to bind the enzyme was determined by EPR and mass spectrometry. EPR Tempol signal decreased in the presence of PDI while remained unaffected when PDI thiols were previously blocked with NEM. When total protein was analyzed, 1 and 4 molecules of Tempol were bound to the protein. However, only one was found to be covalently bound to PDI at the a′active site. More specifically, Cys400 was modified by Tempol. ConclusionWe have shown that the nitroxide Tempol acts as an inhibitor of PDI through covalent binding to the Cys400 of the protein structure. Since PDI is coupled with the assembly of the NADPH oxidase complex of phagocytes, these findings reveal a novel action of Tempol that presents potential clinical applications for therapeutic intervention to target PDI knockdown in pathological processes in which this protein is engaged.

Glibenclamide prevents the attenuation of the exercise pressor reflex by tempol in the ligated rats

In decerebrated rats, ligation of a femoral artery has been shown to exaggerate the exercise pressor reflex, an effect which is attenuated by tempol. The action of tempol has been attributed to its ability to scavenge superoxide radicals. Tempol, in addition, opens ATP sensitive potassium channels, an effect which could also explain its ability to attenuate the exercise pressor reflex in rats with ligated femoral arteries. To test this alternative explanation, we measured the effect of femoral arterial injection of glibenclamide (0.1 mg/kg), which blocks ATP sensitive potassium channels, on the tempol‐induced attenuation of the exercise pressor reflex in decerebrated rats whose femoral arteries had been occluded 72 hours before the start of the experiment. In the first group of rats (n=6), which were not given glibenclamide, tempol attenuated the exercise pressor reflex from 36 ± 5 to 15 ± 2 mmHg (P< 0.05). In the second group of rats (n=8), which were given glibenclamide just before tempol, the superoxide scavenger had no effect on the exercise pressor reflex, which averaged 28 ± 2 mmHg before tempol and 26 ± 2 mmHg afterwards (P> 0.05). We conclude that tempol attenuated the exercise pressor reflex by opening ATP sensitive potassium channels on the endings of group III and IV muscle afferents. Tempol does not appear to attenuate the exaggerated exercise pressor reflex by scavenging superoxide radicals.

Acceleration of diabetic renal injury in the superoxide dismutase knockout mouse: effects of tempol

Indices of renal injury and oxidative stress were examined in mice with deficiency of cytosolic Cu 2+/Zn 2+ superoxide dismutase (SOD1−/−, KO) and their wild-type (WT) littermates with streptozotocin-induced diabetes. After 5 weeks of diabetes, KO diabetic (D) but not WT-D mice developed marked albuminuria, increases in glomerular content of transforming growth factor β, collagen α1(IV), and nitrotyrosine, and higher glomerular superoxide compared with corresponding values in nondiabetics. After 5 months of diabetes, increases in these parameters, mesangial matrix expansion, renal cortical malondialdehyde content, and severity of tubulointerstitial injury were all significantly greater, whereas cortical glutathione was lower, in KO-D than in WT-D. In contrast to WT-D, after 4 weeks of diabetes, KO-D mice did not develop the increase in inulin clearance ( C In) characteristic of early diabetes. The nitric oxide synthase inhibitor N ω-nitro- l-arginine methylester suppressed C In in WT-D, but had no effect on C In in KO-D. Treatment of KO-D with the SOD mimetic tempol for 4 weeks suppressed albuminuria, increases in glomerular transforming growth factor β, collagen α1(IV), nitrotyrosine, and glomerular superoxide, and concurrently increased C In. The latter action of tempol in KO-D was blocked by the N ω-nitro- l-arginine methylester. The findings provide support for a role for superoxide and its metabolism by SOD1 in the pathogenesis of renal injury in diabetes in vivo, and implicate increased interaction of superoxide with nitric oxide as a pathogenetic factor.