P6285Protective effects of exercise on vascular function are mediated by NADPH oxidase 4

Background/Introduction

Physical activity is one of the most potent strategies to prevent endothelial dysfunction. Recent evidence indicates vaso-protective properties of H2O2 produced by main endothelial NADPH oxidase isoform 4 (Nox4) in the vasculature.

Purpose

Therefore, we hypothesized that Nox4 connects physical activity with vaso-protective effects.

Methods and results

Analysis of endothelial function by Mulvany myograph showed endothelial dysfunction in wild-type as well as in Nox4−/− mice after 20 weeks on high-fat diet. Access to voluntary running wheels during high-fat diet prevented endothelial dysfunction in wild-type but not in Nox4−/− mice. Mechanistically, exercise led to increased H2O2 release in the aorta of wild-type mice with increased phosphorylation of eNOS pathway member AKT serine/threonine kinase 1 (Akt1), subsequently. Both effects were diminished in aortas of Nox4−/− mice. Deletion of Nox4 also led to decreased capacity for intracellular calcium release and reduced phenylephrine-mediated contraction, whereas potassium-induced contraction was unaffected. H2O2 scavenger catalase reduced phenylephrine-contraction in wild-type mice. Supplementation of H2O2 increased phenylephrine-induced contraction in Nox4−/− mice. Exercise induced key regulator of mitochondria biogenesis peroxisome proliferative activated receptor gamma, coactivator 1 alpha (Ppargc1a) in wild-type but not Nox4−/− mice. Furthermore, exercise induced citrate synthase activity and reduced mitochondria mass in the absence of Nox4. Thus, Nox4−/− mice became less active and ran less compared with wild-type mice.

Conclusions

Nox4 derived H2O2 plays a key role in exercise-induced adaptations of eNOS and Ppargc1a pathway and intracellular calcium release. Hence, loss of Nox4 diminished physical activity performance and vascular protective effects of exercise.

Acknowledgement/Funding

This work was supported by a research grant of the German Cardiac Society (DGK) (to H.L.) and DFG (Grant MO 1695/4-1 to H.M.).

Benzo(a)pyrene induces lung toxicity and inflammation in mice: prevention by carvacrol

Benzo(a)pyrene (B(a)P) is an environmental pollutant which causes various lung toxicities. The present study was designed to evaluate the protective effects of carvacrol, a monoterpenic phenol against B(a)P-induced lung toxicity. In this study, Swiss albino mice were pretreated with carvacrol (25 mg/kg and 50 mg/kg) orally for 7 consecutive days before administering oral B(a)P (125 mg/kg). Preventive efficacy of carvacrol was assessed in terms of membrane oxidation, antioxidant enzyme activities, histopathological changes, and inflammatory (iNOS, NF-κB, and COX-2) markers. Carvacrol pretreatment in the two doses restored B(a)P-induced lipid peroxidation and increased the activities of antioxidant enzymes. Protein expressions of iNOS, NF-κB, and COX-2 in the lung tissue were found to be upregulated by B(a)P. Carvacrol treatment, however, downregulated their expressions by decreasing the marker of positive stained cells and restored the histopathological architecture of lung tissue. Our results suggest that carvacrol can be used as a protective agent against B(a)P-induced lung toxicity and inflammation.

Amelioration of Benzo[a]pyrene-induced oxidative stress and pulmonary toxicity by Naringenin in Wistar rats: A plausible role of COX-2 and NF-κB

Naringenin is a naturally occurring flavanones and has been found to exhibit free radical scavenging, enzyme inhibition, antioxidants, anti-inflammatory, and anticancer activities. Present study was designed to evaluate the protective role of naringenin against benzo[a]pyrene (B[a]P)-induced oxidative stress and pulmonary toxicity. Rats were treated with naringenin at a dose of 100 mg/kg body weight (b. wt.), by oral gavage. B[a]P in a single dose of 50 mg/kg b. wt. was given intraperitoneally. Total protein, total cell counts, lactate dehydrogenase, lipid peroxidation, reduced glutathione, antioxidant enzymes activities, lung histology and expression of nuclear factor kappa B (NF-κB), and cyclo-oxygenase-2 (COX-2) was assessed to evaluate protective effects of naringenin. Histopathological and immunohistochemical studies were also carried out to observe lung toxicity and inflammation. B[a]P administration enhanced the levels of lung injury markers and reduced antioxidant enzymes activities. Naringenin treatment attenuated the levels of oxidative stress by restoring antioxidant enzymes, further improved lung histological damage and significant decrease in inflammatory responses. Naringenin also effectively decreased the expression of NF-κB, and COX-2 induced by B[a]P. These findings suggest that naringenin supplementation is beneficial in maintaining the integrity of alveoli and the epithelium that may be used as a protective agent in B[a]P-induced oxidative stress and lung damage. However, further studies are warranted to elucidate the potential mechanism of action of naringenin.

18-β Glycyrrhetinic acid alleviates 2-acetylaminofluorene-induced hepatotoxicity in Wistar rats

2-Acetylaminofluorene (2-AAF) is a known hepatic carcinogen which leads to tumour formation in rodents. 18-β Glycyrrhetinic acid (18 β-GA) derived from liquorice plant has various pharmacological properties such as anti-ulcer, anti-inflammatory, antiviral, hepatoprotective and antioxidant. This study is designed to elucidate the chemopreventive properties of 18 β-GA against 2-AAF-induced liver toxicity in Wistar rats and evaluated its effect on inflammatory and tumour promotion marker and activities of different oxidative stress enzymes. Administration of 2-AAF at the dose of (50 mg/kg body weight (b.w.) intraperitoneally (i.p.)) for five consecutive days induces hepatic toxicity, inflammation, oxidative stress and hyperproliferation. Pretreatment with 18 β-GA at two different doses (45 and 75 mg kg−1 b.w.) significantly ameliorates 2-AAF-induced increased lipid peroxidation, alanine transaminase and aspartate transaminase, xanthine oxidase activities and activities of phase-II detoxifying enzymes along with the levels of glutathione content. Administration of 18 β-GA also significantly restored the expressions of proliferating cell nuclear antigen, cyclooxygenase 2, inducible nitric oxide synthase and nuclear factor κB. Furthermore, histological observations also support the preventive effects of 18 β-GA. Our findings suggest that pretreatment with 18 β-GA showed potential hepatoprotective effects via attenuation of oxidative stress, inflammation and hyperproliferation.

Unusual presentation of mycosis fungoides as a lump in the scalp

We report a case of mycosis fungoides in a 27-year-old woman who presented with a lump in the forehead. The condition was confirmed with tissue diagnosis. Gallium scintigraphy accurately delineated the complete extent of the disease, and served as a reference for objective assessment of response of the disease to treatment.

Phase II feasibility of concurrent docetaxel and post mastectomy radiation after four cycles of AC chemotherapy in patients with high risk operable breast cancer: A trial of the Cancer Research Group Pakistan

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Background: Sequential use of docetaxel after four cycles of AC chemotherapy delays the postoperative radiation and can compromise loco-regional control. This delay can be avoided by starting radiotherapy concurrent with the docetaxel. We evaluated the feasibility of concurrent docetaxel and radiation therapy to chest wall and peripheral lymphatics after four cycles of AC chemotherapy. The preliminary results were reported in ASCO 2005 (Abstract 858). Methods: Females between 18–50 years, T2-T3 lesions, four or more positive nodes and hormone receptor negative tumors were eligible. Patients were enrolled after MRM. Four cycles of AC at 60/600 mg/m2 were followed by four cycles of docetaxel at 75mg/m2 every 21-days. Concurrent radiation to chest wall and peripheral lymphatics was started with the third cycle of docetaxel. A dose of 50 Gy in 5 weeks or equivalent was delivered. Successful completion of treatment in 18 out of 20 or 25 out of 30 patients was chosen as an index of feasibility. CTC version 2.0 of NCI and RTOG/EORTC Late Radiation Morbidity Scoring Scheme was used. Results: All the 30 enrolled patients successfully completed the planned treatment. Radiation was completed within 6 months of surgery in 27(90%) of the patients. Febrile neutropenia was seen in 5(16.7%). Grade-3 neutropenia and diarrhea in 8(26.7%) and 6(20%) respectively. Grade-3 dermatitis in the radiated area was seen in 2(6.7%) and grade-2 in 5(16.7%). Late toxicity included grade-2 skin atrophy and telangiectasia in radiated area in 6(20%) each. At a median follow up of 20 months (range 9–25 months) two local recurrences and two systemic relapses have been seen. Conclusion: This treatment schedule is feasible and safe in patients with high-risk operable breast cancer. It allows delivery of post mastectomy radiation within 6 months of surgery in patients undergoing sequential AC-docetaxel chemotherapy.

No significant financial relationships to disclose.