Effect of bismuth subgallate on nitric oxide and prostaglandin E2 production by macrophages

Bismuth subgallate (BSG) is used widely in clinics, including Vincent's angina, syphilis, and adenotonsillectomy. This study examined the effects of BSG on nitric oxide (NO) and prostaglandin E2 (PGE2) production in activated RAW 264.7 cells. BSG suppressed production of NO and PGE2 in a dose-dependent manner. BSG could increase TGF-beta1 production, which in turn might promote degradation of iNOS mRNA, thus inhibiting NO production. Additionally, BSG inhibited mPGES protein expression and COX-2 activity in activated RAW 264.7 cells. Exogenous addition of SNP reversed the inhibition effect of PGE2 production by BSG. This behavior indicates that PGE2 inhibition by BSG exerts an indirect effect through NO inhibition.     

Analysis of the effects of nitric oxide and oxygen on nitric oxide production by macrophages

The interactions between NO and O(2) in activated macrophages were analysed by incorporating previous cell culture and enzyme kinetic results into a novel reaction-diffusion model for plate cultures. The kinetic factors considered were: (i) the effect of O(2) on NO production by inducible NO synthase (iNOS); (ii) the effect of NO on NO synthesis by iNOS; (iii) the effect of NO on respiratory and other O(2) consumption; and (iv) the effects of NO and O(2) on NO consumption by a possible NO dioxygenase (NOD). Published data obtained by varying the liquid depth in macrophage cultures provided a revealing test of the model, because varying the depth should perturb both the O(2) and the NO concentrations at the level of the cells. The model predicted that the rate of NO(2)(-) production should be nearly constant, and that the net rate of NO production should decline sharply with increases in liquid depth, in excellent agreement with the experimental findings. In further agreement with available results for macrophage cultures, the model predicted that net NO synthesis should be more sensitive to liquid depth than to the O(2) concentration in the headspace. The main reason for the decrease in NO production with increasing liquid depth was the modulation of NO synthesis by NO, with O(2) availability playing only a minor role. The model suggests that it is the ability of iNOS to consume NO, as well as to synthesize it, that creates very sensitive feedback control, setting an upper bound on the NO concentration of approximately 1 microM. The effect of NO consumption by other possible pathways (e.g., NOD) would be similar to that of iNOS, in that it would help limit net NO production. The O(2) utilized during enzymatic NO consumption is predicted to make the O(2) demands of activated macrophages much larger than those of unactivated ones (where iNOS is absent); this remains to be tested experimentally.     

Diarylheptanoids from Curcuma kwangsiensis and their inhibitory activity on nitric oxide production in lipopolysaccharide-activated macrophages

Eleven diarylheptanoids (1-11) were isolated from rhizomes of Curcuma kwangsiensis, together with seven known compounds. Their structures were elucidated by 1D and 2D NMR, circular dichroism (CD), and accurate mass measurements. Inhibitory effects of the isolated compounds on nitric oxide production in lipopolysaccaride-activated macrophages were evaluated. Compounds 1, 2, and 3 showed strong inhibitory activity on NO production with IC(50) values of 3.13, 2.81 and 2.41 μM, respectively.     

Endothelial nitric oxide synthase: a determinant of TNFalpha production by human monocytes/macrophages

Until recently endothelial nitric oxide synthase (eNOS) has been associated exclusively with physiological functions, particularly in the cardiovascular system. However, increasing evidence has been accumulated that supports the concept for a role of eNOS in pathophysiology. In particular, detection of eNOS protein and activity in human monocytes/macrophages suggest an immunomodulatory role of this enzyme. Here, we review data that promote the hypothesis that by enhancing TNFalpha production, eNOS activity should be regarded as a novel pro-inflammatory parameter in human monocytes/macrophages.     

Effects of moderate hypothermia on constitutive and inducible nitric oxide synthase activities after traumatic brain injury in the rat

We investigated the effects of therapeutic hypothermia (30 degrees C) on alterations in constitutive (cNOS) and inducible (iNOS) nitric oxide synthase activities following traumatic brain injury (TBI). Male Sprague-Dawley rats were anesthetized with 0.5% halothane and underwent moderate (1.8-2.2 atm) parasagittal fluid-percussion (F-P) brain injury. In normothermic rats (37 degrees C) the enzymatic activity of cNOS was significantly increased at 5 min within the injured cerebral cortex compared with contralateral values (286.5+/-68.9% of contralateral value; mean+/-SEM). This rise in nitric oxide synthase activity was significantly reduced with pretraumatic hypothermia (138.8+/-17% of contralateral value; p < 0.05). At 3 and 7 days after normothermic TBI the enzymatic activity of cNOS was decreased significantly (30+/-8.4 and 28.6+/-20.9% of contralateral value, respectively; p < 0.05). However, immediate posttraumatic hypothermia (3 h at 30 degrees C) preserved cNOS activity at 3 and 7 days (69.5+/-23.3 and 78.6+/-7.6% of contralateral value, respectively; mean+/-SEM; p < 0.05). Posttraumatic hypothermia also significantly reduced iNOS activity at 7 days compared with normothermic rats (0.021+/-0.06 and 0.23+/-0.06 pmol/mg of protein/min, respectively; p < 0.05). The present results indicate that hypothermia (a) decreases early cNOS activation after TBI, (b) preserves cNOS activity at later periods, and (c) prevents the delayed induction of iNOS. Temperature-dependent alterations in cNOS and iNOS enzymatic activities may participate in the neuroprotective effect of hypothermia in this TBI model.     

Curcumin attenuates ovalbumin-induced airway inflammation by regulating nitric oxide

Curcumin has been strongly implicated as an anti-inflammatory agent, but the precise mechanisms of its action are largely unknown. In this study, we show that curcumin contributes to anti-inflammatory activity in the murine asthma model and lung epithelial cell A549 through suppression of nitric oxide (NO). To address this problem, curcumin was injected into the peritoneum of ovalbumin (OVA)-sensitized mice before the last allergen challenge. OVA challenge resulted in activation of the production of inducible nitric oxide (iNOS) in lung tissue, inflammatory cytokines, recruitment of eosinophils to lung airways, and airway hyper-responsiveness to inhaled methacholine. These effects of ovalbumin challenge were all inhibited by pretreatment of mice with curcumin. Furthermore, supplementation with curcumin in the A549 human airway epithelial cells decreased iNOS and NO production induced by IFN-γ. These findings show that curcumin may be useful as an adjuvant therapy for airway inflammation through suppression of iNOS and NO.     

Cobalt-60 gamma radiation increased the nitric oxide generation in cultured rat vascular smooth muscle cells

Radiation is a promising and new treatment for restenosis following angioplasty. Nitric oxide has been proposed as a potential "anti-restenotic" molecule. We radiated the cultured rat vascular smooth muscle cells with Cobalt-60 gamma radiation at doses of 14 and 25Gy and observed nitrite production, cGMP content, L-arginine uptake, inducible nitric oxide synthase (iNOS) activity, and the gene expression of iNOS. Results showed that radiation at doses of 14 and 25Gy increased cGMP content by 92.4% and 86.4%, respectively. Radiation at the dose of 25Gy increased the iNOS activity and nitrite content, but radiation at the dose of 14Gy had no significant effect on iNOS activity and NO production. Both doses of radiation significantly decreased the L-arginine transport. Radiation at the doses of 14 and 25Gy increased iNOS gene expression significantly, which was consistent with the effect of radiation on iNOS activity. In conclusion, radiation induces the NO generation by up-regulating the iNOS activity.     

Nitric oxide produced by iNOS is associated with collagen synthesis in keloid scar formation

Nitric oxide (NO) has emerged as an important mediator of many physiological functions. Recent reports have shown that NO participates in the wound healing process, however, its role in keloid formation remains unclear. This study aimed to investigate the effect of NO on keloid fibroblasts (KF) and to determine the levels of inducible nitric oxide synthase (iNOS) expression in clinical specimens of keloid. Scar tissue from seven keloid patients with matched perilesion skin tissue controls was studied for inducible nitric oxide synthase expression and location. In addition, primary keloid and normal scar skin fibroblast cultures were set up to investigate the effects of NO in inducing collagen type I expression. Inducible nitric oxide synthase expression, and NO production were elevated in keloid scar tissues but not in matched perilesion skin tissues. Furthermore, exposure of KF to exogenous NO resulted in increased expression of collagen type I in a dose-dependent manner. NO exposure also induced time-course dependent collagen I expression that peaked at 24h in KF. Taken together, these results indicate that excess collagen formations in keloid lesion may be attributed to iNOS overexpression.     

Oxidized phospatidylcholine but not native phosphatidylcholine inhibits inducible nitric oxide synthase in RAW 264.7 macrophages

This study was designed to compare the effects of oxidized 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphorylcholine (PAPC) and native PAPC on the inducible nitric oxide synthase (iNOS) in the macrophage cell line RAW 264.7. Macrophages stimulated by bacterial lipopolysaccharide (1 microg/ml) were incubated with increasing amounts of native or oxidized PAPC (oxPAPC, 10-20 microg/ml). Cells incubated with oxPAPC showed a dose-dependent inhibition of inducible nitric oxide synthesis, as well as reduced iNOS protein expression and mRNA levels. Additionally, chromatin immunoprecipitation assay revealed that oxPAPC reduced the interaction of the active NF-kappaB subunit p65 with the iNOS promoter region when compared to native PAPC.     

Expression of N-methyl-d-aspartate receptor and its effect on nitric oxide production of rat alveolar macrophages

We early show that glutamate (Glu) mediate hyperoxia-induced newborn rat lung injury through N-methyl-d-aspartate receptor (NMDAR). In this study, we search for evidence of NMDAR expression on newborn rat alveolar macrophages (AMs) and the difference between newborn and adult rat AMs, and the possible effect on nitric oxide (NO) production of AMs by exogenous NMDA. The protein of NMDAR was showed by immunocytochemistry, and the mRNA was examined by RT-PCR and real-time PCR. The results show that: (i) both newborn and adult rat AMs express NMDAR1 and the four NMDAR2 subtypes and newborn rat AMs are higher expression. (ii) NMDA administration increase NO production, inducible nitric oxide synthase (iNOS) activity and iNOS mRNA expression of AMs. (iii) NMDAR activation elevates NO secretion of AMs, which suggests that AM may be one of the key cellular origin of the elevated NO secretion in hyperoxia-induced lung injury.     

Reactive oxygen and nitrogen species regulate inducible nitric oxide synthase function shifting the balance of nitric oxide and superoxide production

Inducible NOS (iNOS) is induced in diseases associated with inflammation and oxidative stress, and questions remain regarding its regulation. We demonstrate that reactive oxygen/nitrogen species (ROS/RNS) dose-dependently regulate iNOS function. Tetrahydrobiopterin (BH₄)-replete iNOS was exposed to increasing concentrations of ROS/RNS and activity was measured with and without subsequent BH₄ addition. Peroxynitrite (ONOO⁻) produced the greatest change in NO generation rate, ∼95% decrease, and BH₄ only partially restored this loss of activity. Superoxide () greatly decreased NO generation, however, BH₄ addition restored this activity. Hydroxyl radical (OH) mildly decreases NO generation in a BH₄-dependent manner. iNOS was resistant to H₂O₂ with only slightly decreased NO generation with up to millimolar concentrations. In contrast to the inhibition of NO generation, ROS enhanced production from iNOS, while ONOO⁻ had the opposite effect. Thus, ROS promote reversible iNOS uncoupling, while ONOO⁻ induces irreversible enzyme inactivation and decreases both NO and production.     

Quantitative nitric oxide production by rat, bovine and porcine macrophages

The aim of this work was to compare in vitro nitric oxide (NO) production by rat, bovine and porcine macrophages. NO production was induced by lipopolysaccharide (LPS) or by phorbol 12-myristate 13-acetate (PMA) with ionomycin or recombinant interferon gamma (rIFN-γ) and was assessed by Griess reaction. NO synthase type II (NOS II) expression was quantified by immunocytochemistry, Western blot and real-time polymerase chain reaction (RT-PCR). There were differences in NO production by pulmonary alveolar macrophages (PAM) in all species tested. The largest amounts of NO were produced by rat PAM. Less NO was produced by bovine PAM. Moreover, PAM in rats and cows differed in their abilities to respond to various stimulators. Neither porcine PAM nor Kupffer cells produced NO. Stimulation of porcine PAM with alternative concentrations of LPS did not lead to inducing NO production. Stimulation of porcine PAM with rIFN-γ together with LPS led to a significant increase in the expression of NOS II mRNA, albeit without detectable NO production or NOS II expression on the protein level.     

Pharmacological inhibition of inducible nitric oxide synthase attenuates the development of seizures in mice

The present study has been designed to pharmacologically expound the significance of inducible nitric oxide synthase in the pathophysiological progression of seizures using mouse models of chemically induced kindled epilepsy and status epilepticus induced spontaneous recurrent seizures. Pentylenetetrazole (40 mg kg⁻¹) (PTZ) administration every second day for a period of 15 days was used to elicit kindled seizure activity in mice. Severity of kindled seizures was assessed in terms of a composite kindled seizure severity score (KSSS). Pilocarpine (100 mg kg⁻¹) was injected every 20 min until the onset of status epilepticus. A spontaneous recurrent seizure severity score (SRSSS) was recorded as a measure of quantitative assessment of the progressive development of spontaneous recurrent seizures induced after pilocarpine status epilepticus. Sub-acute PTZ administration induced the development of severe form of kindled seizures in mice. Further, pharmacological status epilepticus elicited a progressive evolution of spontaneous recurrent seizures in the animals. However, treatment of aminoguanidine, a relatively selective inhibitor of inducible nitric oxide synthase, markedly and dose dependently suppressed the development of both PTZ induced kindled seizures as well as pilocarpine induced spontaneous recurrent seizures. Therefore inducible nitric oxide synthase may be implicated in the development of seizures.     

昆虫一氧化氮及其合酶的研究进展

一氧化氮作为一种重要的信息分子 ,参与调节昆虫嗅觉、视觉、机械感受、发育、机体防御及学习行为。该文从生理、生化、形态定位以及信号转导几方面综述了有关昆虫一氧化氮及其合酶的最新研究进展。