Evaluation of the relationship between inducible nitric oxide synthase (iNOS) activity and effects of melatonin in experimental osteoporosis in the rat

We tested the hypothesis that osteopontin (OPN) can inhibit the induction of inducible nitric oxide synthase (iNOS) in vascular tissue. iNOS activity was induced in rat thoracic aortas by incubation of the tissue with lipopolysaccharide (LPS) and measured by conversion ofl-[3H]arginine tol-[3H]citrulline. Addition of ≥1 nM recombinant OPN protein significantly reduced the LPS-induced increase in iNOS activity. Western blotting and the RT-PCR were used to determine the effect of LPS with and without OPN on tissue levels of iNOS protein and RNA, respectively. LPS resulted in an increase in iNOS protein and RNA, whereas OPN dose-dependently reduced tissue levels of iNOS activity, protein, and RNA. Mutated OPN proteins, in which the integrin-binding RGD amino acid sequence was deleted or mutated to RGE, resulted in complete and partial loss, respectively, of the ability of OPN to inhibit LPS-induced iNOS activity, implicating integrin binding in the effect. These results indicate that OPN can prevent induction of iNOS in vascular tissue.

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The potential role of inducible nitric oxide synthase (iNOS) activity in the testicular dysfunction associated with varicocele: An experimental study

International Urology and Nephrology ◽

10.1023/b:urol.0000032687.58462.4f ◽

2004 ◽

Vol 36 (1) ◽

pp. 67-72 ◽

Cited By ~ 14

Author(s):

İsmail Türker Köksal ◽

Tibet Erdoğru ◽

Hakan Gülkesen ◽

Cem Sezer ◽

Mustafa Usta ◽

...

Keyword(s):

Nitric Oxide ◽

Experimental Study ◽

Nitric Oxide Synthase ◽

Inducible Nitric Oxide Synthase ◽

Potential Role ◽

Inos Activity ◽

Testicular Dysfunction ◽

Oxide Synthase ◽

Inducible Nitric Oxide

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Heme Oxygenase-1 Induction Attenuates Inducible Nitric Oxide Synthase Expression and Proteinuria in Glomerulonephritis

Journal of the American Society of Nephrology ◽

10.1681/asn.v10122540 ◽

1999 ◽

Vol 10 (12) ◽

pp. 2540-2550

Author(s):

PRASUN K. DATTA ◽

SEVASTI B. KOUKOURITAKI ◽

KATHLEEN A. HOPP ◽

ELIAS A. LIANOS

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Heme Oxygenase ◽

Inducible Nitric Oxide Synthase ◽

Inos Expression ◽

Heme Oxygenase 1 ◽

Inos Activity ◽

Protein Levels ◽

Oxide Synthase ◽

Inducible Nitric Oxide

Abstract. In glomerulonephritis, there is intraglomerular activation of inducible nitric oxide synthase (iNOS) leading to high output production of nitric oxide (NO). This can result in supraphysiologic amounts of NO and cause oxidative injury. It is unknown whether mechanisms of cellular defense against NO-mediated injury exist. Induction of the heme catabolizing enzyme heme oxygenase-1 (HO-1), which generates biliverdin, carbon monoxide (CO), and iron (Fe), may provide such a mechanism, as CO and Fe are two negative modulators of iNOS activity and expression. This study assessed whether upregulation of HO-1 by a specific inducer, hemin, negatively modulates iNOS expression and activity in anti-glomerular basement membrane antibody-mediated glomerulonephritis. Glomerular HO-1 expression in nephritic animals was upregulated by treatment with hemin (30 μmol/kg body wt). iNOS and HO-1 mRNA expression were assessed by reverse transcription-PCR of glomerular total RNA from nephritic animals or nephritic animals pretreated with hemin. iNOS activity in glomeruli was measured by assessing conversion of [14C] L-arginine to [14C] L-citrulline. HO-1 protein levels in glomeruli were assessed by Western blot analysis. The effect of hemin treatment on monocyte/macrophage infiltration was assessed by enumeration of ED-1-positive cells in nephritic glomeruli. iNOS and HO-1 were coinduced in nephritic glomeruli. Hemin treatment of nephritic animals resulted in upregulation of glomerular HO-1 levels and a two- to threefold reduction in glomerular iNOS mRNA levels. iNOS activity in glomeruli was significantly reduced in hemin-treated nephritic animals in which proteinuria was also attenuated without a change in monocyte/macrophage infiltration. Hemin (100 to 200 μM) also reduced iNOS protein levels and enzyme activity in cultured mesangial cells stimulated with cytokines. These studies demonstrate that in glomerular immune injury, hemin treatment upregulates glomerular HO-1 with an attendant downregulation of iNOS expression, and thus points to regulatory interaction between the two systems. The beneficial effect of hemin treatment on proteinuria could be linked to downregulation of iNOS.

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Chlamydia trachomatis Persistence in the Female Mouse Genital Tract: Inducible Nitric Oxide Synthase and Infection Outcome

Infection and Immunity ◽

10.1128/iai.69.8.5131-5137.2001 ◽

2001 ◽

Vol 69 (8) ◽

pp. 5131-5137 ◽

Cited By ~ 50

Author(s):

Kyle H. Ramsey ◽

Gurwattan S. Miranpuri ◽

Ira M. Sigar ◽

Scott Ouellette ◽

Gerald I. Byrne

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Chlamydia Trachomatis ◽

Inducible Nitric Oxide Synthase ◽

Genital Tract ◽

Lung Fibroblasts ◽

Inos Activity ◽

Ifn Γ ◽

Oxide Synthase ◽

Inducible Nitric Oxide

ABSTRACT It was previously reported that female mice resolve a primaryChlamydia trachomatis urogenital infection independent of inducible nitric oxide synthase (iNOS). We now report that although iNOS-deficient (NOS2−/−) mice resolve culture-apparent infection in a fashion similar to that of normal control (NOS2 +/+) mice, they sustain significantly increased rates of disease, as assessed by hydrosalpinx formation. PCR amplification of ompAfollowed by Southern blot detection of amplicands revealed the presence of chlamydial DNA in the lower genital tracts of both NOS2−/− and NOS2 +/+ mice at ≥120 days postinfection and in upper genital tract tissues at >120 days postinfection. However, only NOS2−/− mice shed low numbers of viable chlamydiae from the lower genital tract after immunosuppressive treatment at 120 days postinfection. When cultured primary murine lung fibroblasts were activated in the presence of gamma interferon (IFN-γ), inhibition of chlamydial growth occurred in both NOS2 +/+ and NOS2−/− cells, but the inhibition was reversible after removal of the cytokine in the NOS2−/− primary cell culture only. The iNOS-independent inhibition was microbistatic but was independent of 2,3-indoleamine dioxygenase activity. We conclude that chlamydial DNA and antigens persist in mice subsequent to culture-apparent resolution. In addition, IFN-γ induces in vivo inhibition of chlamydial growth through microbistatic mechanisms in the absence of iNOS activity, but in the presence of iNOS activity, IFN-γ is microbicidal and effects eradication.

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Inhibition of cytokine-induced inducible nitric oxide synthase expression by glucagon and cAMP in cultured hepatocytes

Biochemical Journal ◽

10.1042/bj3260187 ◽

1997 ◽

Vol 326 (1) ◽

pp. 187-192 ◽

Cited By ~ 20

Author(s):

Fiona S. SMITH ◽

Enrico D. CEPPI ◽

Michael A. TITHERADGE

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Inducible Nitric Oxide Synthase ◽

Interferon Γ ◽

Significant Inhibition ◽

Covalent Modification ◽

Cultured Hepatocytes ◽

Inos Activity ◽

Oxide Synthase ◽

Inducible Nitric Oxide

Addition of lipopolysaccharide plus interferon γ, tumour necrosis factor α and interleukin 1β to cultured hepatocytes resulted in the induction of inducible nitric oxide synthase (iNOS) activity as measured by NO3-+NO2- formation, the conversion of L-[U-14C]arginine into citrulline and Western blotting of the iNOS protein. The inclusion of 1 μM glucagon during the induction period significantly decreased the effect of the cytokines on iNOS activity, the major effect being at the level of the total amount of protein, rather than alterations in substrate supply or covalent modification of the existing protein. In contrast, 1 μM insulin was without effect. The effect of glucagon was mediated via cAMP and could be mimicked by the presence of either dibutyryl cAMP or forskolin to activate adenylate cyclase directly. It was rapid in onset and long-lived, a 30 min pre-treatment period protecting the cells from the induction of NO synthesis over the next 21 h in the presence of cytokines. Addition of glucagon at any time point up to 9 h after treatment of the cells with lipopolysaccharide plus the cytokines resulted in a significant inhibition of iNOS activity, glucagon being most potent when added during the first 3 h.

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Atorvastatin-induced cardioprotection is mediated by increasing inducible nitric oxide synthase and consequent S-nitrosylation of cyclooxygenase-2

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01137.2005 ◽

2006 ◽

Vol 290 (5) ◽

pp. H1960-H1968 ◽

Cited By ~ 98

Author(s):

Shaul Atar ◽

Yumei Ye ◽

Yu Lin ◽

Sheldon Y. Freeberg ◽

Shawn P. Nishi ◽

...

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Inducible Nitric Oxide Synthase ◽

Left Ventricular ◽

Sprague Dawley ◽

Area At Risk ◽

Inos Activity ◽

Cox 2 ◽

Oxide Synthase ◽

Inducible Nitric Oxide

We determined the effects of cyclooxygenase-1 (COX-1; SC-560), COX-2 (SC-58125), and inducible nitric oxide synthase (iNOS; 1400W) inhibitors on atorvastatin (ATV)-induced myocardial protection and whether iNOS mediates the ATV-induced increases in COX-2. Sprague-Dawley rats received 10 mg ATV·kg−1·day−1 added to drinking water or water alone for 3 days and received intravenous SC-58125, SC-560, 1400W, or vehicle alone. Anesthesia was induced with ketamine and xylazine and maintained with isoflurane. Fifteen minutes after intravenous injection rats underwent 30-min myocardial ischemia followed by 4-h reperfusion [infarct size (IS) protocol], or the hearts were explanted for biochemical analysis and immunoblotting. Left ventricular weight and area at risk (AR) were comparable among groups. ATV reduced IS to 12.7% (SD 3.1) of AR, a reduction of 64% vs. 35.1% (SD 7.6) in the sham-treated group ( P < 0.001). SC-58125 and 1400W attenuated the protective effect without affecting IS in the non-ATV-treated rats. ATV increased calcium-independent NOS (iNOS) [11.9 (SD 0.8) vs. 3.9 (SD 0.1) × 1,000 counts/min; P < 0.001] and COX-2 [46.7 (SD 1.1) vs. 6.5 (SD 1.4) pg/ml of 6-keto-PGF1α; P < 0.001] activity. Both SC-58125 and 1400W attenuated this increase. SC-58125 did not affect iNOS activity, whereas 1400W blocked iNOS activity. COX-2 was S-nitrosylated in ATV-treated but not sham-treated rats or rats pretreated with 1400W. COX-2 immunoprecipitated with iNOS but not with endothelial nitric oxide synthase. We conclude that ATV reduced IS by increasing the activity of iNOS and COX-2, iNOS is upstream to COX-2, and iNOS activates COX-2 by S-nitrosylation. These results are consistent with the hypothesis that preconditioning effects are mediated via PG.

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