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Chronic NF-?B blockade improves renal angiotensin II type 1 receptor functions and reduces blood pressure in Zucker diabetic rats.

ABSTRACT: Both angiotensin II type 1 receptor (AT1R) and nuclear factor-kappa B (NF-?B) play significant roles in the pathogenesis of hypertension and type 2 diabetes. However, the role of NF-?B in perpetuating renal AT1 receptors dysfunction remains unclear. The aim of the present study to determine whether blockade of NF-?B, could reverse the exaggerated renal AT1R function, reduce inflammatory state and oxidative stress, lower blood pressure in Zucker diabetic fatty (ZDF) rats.Pyrrolidine dithiocarbamate (PDTC), a NF-?B inhibitor (150 mg/kg in drinking water)or vehicle was administered orally to 12-weeks-old ZDF rats and their respective control lean Zucker (LZ) rats for 4 weeks. Blood pressure was measured weekly by tail-cuff method. AT1R functions were determined by measuring diuretic and natriuretic responses to AT1R antagonist (candesartan; 10 ?g/kg/min iv). The mRNA and protein levels of NF-?B, oxidative stress maker and AT1R were determined using quantitative real-time PCR and Western blotting, respectively. The NF-?B-DNA binding activity in renal cortex was measured by Electrophoretic mobility shift assay (EMSA).As compared with LZ rats, ZDF rats had higher blood pressure, impaired natriuresis and diuresis, accompanied with higher levels of oxidative stress and inflammation. Furthermore, AT1R expression was higher in renal cortex from ZDF rats; candesartan induced natriresis and diuresis, which was augmented in ZDF rats. Treatment with PDTC lowered blood pressure and improved diuretic and natriuretic effects in ZDF rats; meanwhile, the increased oxidative stress and inflammation were reduced; the increased AT1R expression and augmented candesartan-mediated natriuresis and diuresis were recoverd in ZDF rats. Our further study investigated the mechanisms of PDTC on AT1R receptor expression. It resulted that PDTC inhibited NF-?B translocation from cytosol to nucleus, inhibited binding of NF-?B with AT1R promoter, therefore, reduced AT1R expression and function.Our present study indicates blockade of NF-?B, via inhibition of binding of NF-?B with AT1R promoter, reduces renal AT1R expression and function, improves oxidative stress and inflammatory/anti-inflammatory balance, therefore, lowers blood pressure and recovers renal function in ZDF rats.

SUBMITTER: Luo H

PROVIDER: S-EPMC4465496 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Project description:Diabetes is a very strong predictor of chronic systemic vascular diseases and acute cardiovascular events. Recently, associations between metabolic disorders and pulmonary hypertension have also been reported in both humans and animal models. In order to get some further insight into the relationship of pulmonary hypertension with obesity, insulin resistance and hyperglycemia, herein we have used the Zucker diabetic fatty rats (ZDF/clr-lepr fa) at 20 weeks fed a standard diet and compared to their lean Zucker littermates (ZL). ZDF rats were obese, had elevated plasma glucose levels and insulin resistance, i.e. a clinically relevant model of type 2 diabetes. They presented elevated systolic, diastolic and mean pulmonary arterial pressures and a parallel increase in the Fulton index. Systemic arterial pressures were also increased but the left ventricle plus septum weight was similar in both groups and the heart rate was reduced. Wall media thickening was observed in the small pulmonary arteries from the ZDF rats. Isolated pulmonary arteries mounted in a wire myograph showed similar vasoconstrictor responses to phenylephrine and 5-HT and similar responses to the endothelium-dependent vasodilator acetylcholine. However, the iNOS inhibitor 1400W enhanced the vasoconstrictor responses in ZDF but not in ZL rats. The protein expression of eNOS and iNOS was not significantly different in the lungs of the two groups. The lung expression of Bmpr2 mRNA was downregulated. However, the mRNA expression of Kcna5, Kcnk3, Kcnq1, Kcnq4 or Kcnq5, which encode for the potassium channels Kv1.5, TASK-1, Kv7.1, Kv7.4 and Kv7.5, respectively, was similar in ZL and ZDF rats. In conclusion, ZDF rats show increased pulmonary arterial pressure, right ventricular hypertrophy, pulmonary arterial medial thickening and downregulated lung Bmpr2 despite leptin resistance. These changes were mild but are consistent with the view that diabetes is a risk factor for pulmonary hypertension.

Project description:Elevations in plasma levels of pro-inflammatory cytokines and C-reactive protein (CRP) in patient blood have been associated with impairments in cognitive abilities and more severe psychiatric symptoms in people with schizophrenia. The transcription factor nuclear factor kappa B (NF-κB) regulates the gene expression of pro-inflammatory factors whose protein products trigger CRP release. NF-κB activation pathway mRNAs are increased in the brain in schizophrenia and are strongly related to neuroinflammation. Thus, it is likely that this central immune regulator is also dysregulated in the blood and associated with cytokine and CRP levels. We measured levels of six pro-inflammatory cytokine mRNAs and 18 mRNAs encoding NF-κB pathway members in peripheral blood leukocytes from 87 people with schizophrenia and 83 healthy control subjects. We then assessed the relationships between the alterations in NF-κB pathway genes, pro-inflammatory cytokine and CRP levels, psychiatric symptoms and cognition in people with schizophrenia. IL-1β and IFN-γ mRNAs were increased in patients compared to controls (both p < 0.001), while IL-6, IL-8, IL-18, and TNF-α mRNAs did not differ. Recursive two-step cluster analysis revealed that high levels of IL-1β mRNA and high levels of plasma CRP defined 'high inflammation' individuals in our cohort, and a higher proportion of people with schizophrenia were identified as displaying 'high inflammation' compared to controls using this method (p = 0.03). Overall, leukocyte expression of the NF-κB-activating receptors, TLR4 and TNFR2, and the NF-κB subunit, RelB, was increased in people with schizophrenia compared to healthy control subjects (all p < 0.01), while NF-κB-inducing kinase mRNAs IKKβ and NIK were downregulated in patients (all p < 0.05). We found that elevations in TLR4 and RelB appear more related to inflammatory status than to a diagnosis of schizophrenia, but changes in TNFR2 occur in both the high and low inflammation patients (but were exaggerated in high inflammation patients). Further, decreased leukocyte expression of IKKβ and NIK mRNAs was unique to high inflammation patients, which may represent schizophrenia-specific dysregulation of NF-κB that gives rise to peripheral inflammation in a subset of patients.

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Chronic NF-?B blockade improves renal angiotensin II type 1 receptor functions and reduces blood pressure in Zucker diabetic rats.

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