Inducible Nitric Oxide Synthase Activity Research Articles

Anti-Inflammatory Effect of Titrated Extract of Centella asiatica in Phthalic Anhydride-Induced Allergic Dermatitis Animal Model.

Centella asiatica has potent antioxidant and anti-inflammatory properties. However, its anti-dermatitic effect has not yet been reported. In this study, we investigated the anti-dermatitic effects of titrated extract of Centella asiatica (TECA) in a phthalic anhydride (PA)-induced atopic dermatitis (AD) animal model as well as in vitro model. An AD-like lesion was induced by the topical application of five percent PA to the dorsal skin or ear of Hos:HR-1 mouse. After AD induction, 100 μL of 0.2% and 0.4% of TECA (40 μg or 80 μg/cm2) was spread on the dorsum of the ear or back skin three times a week for four weeks. We evaluated dermatitis severity, histopathological changes and changes in protein expression by Western blotting for inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and NF-κB activity, which were determined by electromobility shift assay (EMSA). We also measured TNF-α, IL-1β, IL-6, and IgE concentration in the blood of AD mice by enzyme-linked immunosorbent assay (ELISA). TECA treatment attenuated the development of PA-induced atopic dermatitis. Histological analysis showed that TECA inhibited hyperkeratosis, mast cells and infiltration of inflammatory cells. TECA treatment inhibited expression of iNOS and COX-2, and NF-κB activity as well as the release of TNF-α, IL-1β, IL-6, and IgE. In addition, TECA (1, 2, 5 μg/mL) potently inhibited Lipopolysaccharide (LPS) (1 μg/mL)-induced NO production, expression of iNOS and COX-2, and NF-κB DNA binding activities in RAW264.7 macrophage cells. Our data demonstrated that TECA could be a promising agent for AD by inhibition of NF-κB signaling.

Effect of dietary Clostridium butyricum on growth, intestine health status and resistance to ammonia stress in Pacific white shrimp Litopenaeus vannamei

The present study evaluated the effect of dietary Clostridium butyricum (CB) on growth, intestine microstructure, intestine digestive and immune function, intestine short-chain fatty acids (SCFA) content and body composition of Pacific white shrimp Litopenaeus vannamei. The shrimp was fed for 56 d with diets containing different levels of C. butyricum (1 × 109 cfu/g): 0% (Control), 0.25% (CB1), 0.5% (CB2) and 1.0% (CB3) as treatment groups, followed by an acute ammonia stress test for 72 h. The results indicated that dietary supplementation of C. butyricum decreased the feed conversion rate (FCR) and increased the growth performance of shrimp. Compared with the control group, after shrimp fed with C. butyricum 56 d, intestine amylase and protease activity in the three C. butyricum group increased, while lipase activity was only affected in the CB1 and CB2 group. Total antioxidant capacity (T-AOC) content, lysozyme (LSZ) activity, and the relative expression level of Toll and immune deficiency (Imd) gene all increased in three C. butyricum groups. Inducible nitric oxide synthase (iNOS) activity increased in the CB2 and CB3 group, heat shock protein 70 (HSP70) gene expression level increased in the CB3 group, while nitric oxide (NO) content was not affected by C. butyricum. After shrimp exposed to ammonia stress, intestine immune biochemical parameters (T-AOC, LSZ, iNOS and NO) and genes (HSP70, Toll and Imd) expression level of C. butyricum group was higher than that of the control. HE stain showed that C. butyricum increased the intestine epithelium height of L. vannamei. These results revealed that C. butyricum could improve the growth performance, increased intestine SCFA content and body crude protein content, modulated intestine digestive capacity, and enhanced intestine immune function of L. vannamei against ammonia stress.

Microvascular Endothelial Dysfunction in Obesity Is Driven by Macrophage-Dependent Hydrogen Sulfide Depletion.

The function of perivascular adipose tissue as an anticontractile mediator in the microvasculature is lost during obesity. Obesity results in inflammation and recruitment of proinflammatory macrophages to the perivascular adipose tissue that is paralleled by depletion of the vasorelaxant signaling molecule hydrogen sulfide (H2S) in the vessel. The current objective was to assess the role of macrophages in determining vascular [H2S] and defining how this impinged on vasodilation. Contractility and [H2S] were measured in mesenteric resistance arterioles from lean and obese mice by using pressure myography and confocal microscopy, respectively. Vasodilation was impaired and smooth muscle and endothelial [H2S] decreased in vessels from obese mice compared with those from lean controls. Coculturing vessels from lean mice with macrophages from obese mice, or macrophage-conditioned media, recapitulated obese phenotypes in vessels. These effects were mediated by low molecular weight species and dependent on macrophage inducible nitric oxide synthase activity. The inducible nitric oxide synthase activity of perivascular adipose tissue-resident proinflammatory macrophages promotes microvascular endothelial dysfunction by reducing the bioavailability of H2S in the vessel. These findings support a model in which vascular H2S depletion underpins the loss of perivascular adipose tissue anticontractile function in obesity.

Curcumin inhibits angiotensin II-induced inflammation and proliferation of rat vascular smooth muscle cells by elevating PPAR-γ activity and reducing oxidative stress.

AngiotensinII (AngII)-induced production of inflammatory factors and proliferation in vascular smooth muscle cells (VSMCs) play an important role in the progression of atherosclerotic plaques. Growing evidence has demonstrated that activation of peroxisome proliferator-activated receptor-γ (PPAR-γ) effectively attenuates AngII-induced inflammation and intercellular reactive oxygen species(iROS) production. Curcumin (Cur) inhibits inflammatory responses by enhancing PPAR-γ activity and reducing oxidative stress in various tissues. The aim of the present study was to ascertain whether Cur inhibits AngII-induced inflammation and proliferation, and its underlying molecular mechanism, in VSMCs. Enzyme-linked immunosorbent assay (ELISA) and real-time PCR were used to measure the protein and mRNA expression of interleukin-6 (IL-6) and tumor necrosis factor-α(TNF-α). Nitric oxide(NO) production was measured by Griess reaction. Western blot analysis and a DNA-binding assay were used to measure PPAR-γ activity. iROS production was measured using the DCFH-DA method. In rat VSMCs, Cur attenuated AngII‑induced expression of IL-6 and TNF-α mRNA and protein in a concentration-dependent manner, inhibited NO production by suppressing inducible NO synthase(iNOS) activity, and suppressed proliferation of VSMCs. This was accompanied by increased PPAR-γ expression and activation in Cur-pretreated VSMCs. GW9662, a PPAR-γ antagonist, reversed the anti-inflammatory effect of Cur. Moreover, Cur attenuated AngII-induced oxidative stress by downregulating the expression of p47phox, which is a key subunit of nicotinamide adenine dinucleotide phosphate(NADPH) oxidase. In conclusion, Cur inhibited the expression of IL-6 and TNF-α, decreased the production of NO, and suppressed the proliferation of VSMCs, by elevating PPAR-γ activity and suppressing oxidative stress, leading to attenuated AngII-induced inflammatory responses in VSMCs.

N-Propyl gallate suppresses lipopolysaccharide-induced inducible nitric oxide synthase activation through protein kinase Cδ-mediated up-regulation of heme oxygenase-1 in RAW264.7 macrophages

n-Propyl gallate is a synthetic phenolic antioxidant with potential anti-inflammatory effects. However, the underlying mechanism remains largely unknown. In the present study, we showed that n-propyl gallate increases the expression and activity of the heme oxygenase-1 (HO-1), a stress-inducible protein with potent anti-inflammatory activity, in RAW264.7 macrophages. The inhibition of the HO-1 activity by treatment with zinc (II) protoporphyrin IX (ZnPP) or by knockdown of the HO-1 expression with small interference RNA significantly reversed the inhibitory effect of n-Propyl gallate on activations of nuclear factor-κB (NF-κB) and inducible nitric oxide synthase (iNOS) induced by lipopolysaccharide (LPS). An additional mechanism study using inhibitors of signaling kinases revealed the involvement of protein kinase Cδ (PKCδ) in the expression of HO-1 induced by n-Propyl gallate. Consistent with these results, n-Propyl gallate increased the intracellular levels of phosphorylated PKCδ in concentration- and time-dependent manners. The inhibitory effects of n-Propyl gallate on LPS-induced iNOS expression and nitric oxide production were also significantly attenuated by pretreatment with the PKCδ inhibitor, rottlerin, or by transfection with PKCδ (K376R), a kinase-inactive form of PKCδ. Taken together, these findings provide the first evidence that n-Propyl gallate exerts its anti-inflammatory effect through PKCδ-mediated up-regulation of HO-1 in macrophages.

Effects of hydrogen sulfide on NO content and iNOS activity in diaphragm from type 1 diabetic rats

To investigate the effects of hydrogen sulfide (H2S) on nitric oxide (NO) content and inducible nitric oxide syn-thase (iNOS) activity in diaphragm from type 1 diabetic rats. Thirty-two male SD rats were randomly divided into four groups:nor-mal control group (NC), diabetes mellitus group (DM), DM treatment group (DM + NaHS) and NaHS control group (NaHS) (n=8). Rats were treated with streptozotocin 55 mg/kg by intraperitoneal injection to establish type 1 diabetic rat model. The fourth week after the model-ing, the rats in the DM + NaHS and NaHS groups were treated with 14μmol/kg NaHS solution by intraperitoneally injected. After treatment for 5 weeks, fasting blood glucose (FBG) and diaphragm weight (DW)/body weight (BW) were measured. The pathological changes of draphrag-matic tissues were observed by HE staining. The activity of iNOS was analyzed by spectrophotometric method, while the content of NO was measured by nitric acid reductase method. The iNOS expressions at mRNA and protein levels in diaphragmatic tissues were detected by RT-PCR and Western blot respectively. Compared with the NC group, there was no significant difference in the various indexes in the NaHS group. While FBG was increased significantly, DW/BW was decreased obviously in the DM group. HE staining revealed obvious changes in diaphragmatic tissues. The activity of iNOS and the content of NO were increased. The levels of iNOS mRNA and protein were in-creased significantly. Compared with the DM group, DW/BW and pathological damages were improved in the DM + NaHS group. The activity of iNOS and NO content were decreased significantly. The levels of iNOS mRNA and protein were decreased obviously. Exoge-nous H2S can suppress iNOS activity and expression to decrease the content of NO, which improving the capacity of diaphragm in type 1 diabet-ic rats.

Evaluation of some biological activities of Abelia triflora R Br (Caprifoliaceae) constituents

Purpose: To investigate the antioxidant, anti-inflammatory, antidiabetic, cardiovascular and cytotoxic activities of the leaf extract and major compounds isolated from Abelia triflora R. Br. (Caprifoliaceae)Methods: The chloroform soluble fraction of A. triflora leaves was subjected to several column chromatographic separations to isolate its constituents. Anti-inflammatory and antioxidant activities were determined in terms of the ability to inhibit NF-kB, iNOS activity and lipoxygenase enzyme, and to decrease oxidative stress in HepG2 cells. Antidiabetic and cardiovascular activities were determined by screening for peroxisome proliferator-activated receptor alpha (PPARα) and PPARɣ agonistic activities. In vitro cytotoxic activity was determined against a set of four human cancer cell lines (SK-MEL, KB, BT-549, SK-OV-3) and two non-cancerous kidney cell lines (LLC-PK1 and VERO). Cell viability was measured by neutral red assay.Results: Three triterpene acids were isolated from the chloroform fraction namely; ursolic acid (4), 2, 3-dihydroxy ursolic acid (5) and 2, 3, 21-trihydroxy ursolic acid (6). The results showed that ursolic acid exhibited potent inhibition of lipoxygenase enzyme and iNOS (inducible nitric oxide synthase) activity with IC50 (half-maximal inhibitory concentration) value of 13.0 μg/mL, compared to parthenolide positive standard (IC50, 0.3μg/mL); furthermore, it inhibited NF-kB (nuclear factor-kappa B) with IC50 of 25.0 μg/mL, compared to parthenolide (positive standard, (IC50, 0.5 μg/mL). Also, ursolic acid possessed the highest cytotoxic effect against the three cell lines, SK-MEL (IC50, 14.5 μg/mL), BT-549 (IC50, 16.0 μg/mL) and SK-OV-3 (IC50, 12.5 μg/mL). Only 2,3-dihydroxy ursolic acid activated PPARɣ (1.5-fold at 25 μM), compared to rosiglitazone (positive standard, 3.7 fold at 10 μM)Conclusion: Among the investigated compounds, ursolic acid exhibited the highest anti-inflammatory and cytotoxic activities, while 2,3-dihydroxy ursolic acid demonstrated antidiabetic activity via activation of PPARɣ.Keywords: Abelia triflora, Anti-inflammatory, Antidiabetic, Cardiovascular activity, Antioxidant, Cytotoxic

Intestine oxidative stress and immune response to sulfide stress in Pacific white shrimp Litopenaeus vannamei

The effects of sulfide stress on oxidative stress and immune response in intestine of Pacific white shrimp Litopenaeus vannamei were evaluated in the present study. Oxidative stress parameters, immune enzymes activity and immune gene mRNA expression level were detected in intestine of L. vannamei after the exposure of 5.0 mg/L sulfide stress 72 h. The duration of sulfide stress influenced the shrimp survival, and the cumulative mortality rate was 30.0% and 33.3% at 48 h and 72 h respectively. HE staining showed that sulfide stress caused the intestine tissue damage symptoms. Compared with the control group, after exposed to sulfide stress, the content of lipid peroxidation (LPO), malondialdehyde (MDA) and ROS production (·O2− generation capacity) increased. Total antioxidant capacity (T-AOC) activity increased at 6 h and decreased at 48 h. Superoxide dismutase (SOD) activity increased in the entire experiment. Inducible nitric oxide synthase (iNOS) activity and nitric oxide (NO) content increased to the highest at 6 h and 12 h respectively, and both decreased at 48 h. The relative mRNA expression level of heat shock protein 70 (HSP70) gene decreased at 6 h and increased to the highest at 48 h. The relative mRNA expression level of hypoxia inducible factor 1α (HIF-1α) gene increased at 12 h and decreased to a lower level at 72 h. The relative mRNA expression level of Toll and immune deficiency (Imd) gene increased to the highest at 12 h and 24 h respectively, and both decreased at 48 h. These results revealed that sulfide stress could induce oxidative stress and immune response via confusion of immune enzymes activity and gene expression level in intestine of L. vannamei.

A potential mechanism for the ameliorative effect of thymoquinone on pentylenetetrazole-induced kindling and cognitive impairments in mice.

Cognitive dysfunction is commonly observed in epileptic patients. Pentylenetetrazole (PTZ) kindling is a well established animal model which simulates clinical epilepsy. This study evaluated the potential role of glutamate, oxidative stress and nitric oxide (NO) overproduction in pentylenetetrazole (PTZ)-induced kindling and associated cognitive impairments in mice and effect of thymoquinone on these parameters. Repeated treatment of mice with a subconvulsive dose of PTZ (35mg/kg i.p.) once every alternate-day for 12 injections induced kindling. PTZ-kindled mice showed learning and memory impairments as assessed by acquisition and probe trials of Morris water maze and step-through latency of passive avoidance tests. Concurrently, the brain glutamate, malondialdehyde and nitrite levels were increased while the brain intracellular reduced glutathione level and glutathione peroxidase activity were decreased in PTZ-kindled mice. Also, the brain inducible but not neuronal NO synthase mRNA and protein expressions were increased in PTZ-kindled mice. Treatment of mice with thymoquinonne (5, 10 and 20mg/kg i.p.) along with alternate-day subconvulsive dose of PTZ produced dose-dependent protection against PTZ-induced kindling and learning and memory impairments. Moreover, treatment of mice with thymoquinonne (20mg/kg) inhibited the biochemical alterations induced by PTZ in the brain except the elevation of brain glutamate level. The associated increase in brain inducible NO synthase mRNA and protein expressions were also inhibited. These results suggest that glutamate, and subsequent oxidative stress and NO overproduction, via inducible NO synthase, play an important role in the pathophysiology of PTZ-induced kindling and cognitive impairments in mice. Thymoquinone dose-dependently protects against PTZ-induced kindling and cognitive impairments. Inhibition of PTZ-induced brain oxidative stress and NO overproduction, via increase the expression and activity of inducible NO synthase, may play an important role in thymoquinone action.

The Effect of Selenium on the Cd-Induced Apoptosis via NO-Mediated Mitochondrial Apoptosis Pathway in Chicken Liver

Cd-induced apoptosis and the protective effects of Se against Cd-induced injury have been reported in previous studies. However, little is known regarding the effects of Cd-induced apoptosis in hepatic cells and the antagonistic effects of Se on Cd in poultry. In the present study, 128 healthy 31-week-old laying hens were randomly divided into four groups, which were fed basic diets, with the addition of Se (Na2SeO3, 2mg/kg), Cd (CdCl2, 150mg/kg), or Se + Cd (150mg/kg of CdCl2 and 2mg/kg of Na2SeO3) for 90days. Ultrastructural changes, nitric oxide (NO) concentrations, inducible nitric oxide synthase (iNOS) activities, results of the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay of apoptosis, and the expression of iNOS and apoptosis-related genes in livers were determined. It was observed that Cd treatment significantly increased the concentrations of NO and iNOS activity in chicken livers. The production of excessive NO initiated the mitochondrial apoptotic pathway. Exposure to Cd increased the mRNA and the protein expression levels of iNOS, caspase-3, Bax, p53, and Cyt-c. Furthermore, the ratio of Bax/Bcl-2 increased, while the expression of Bcl-2 decreased. Treatment with Se significantly alleviated Cd-induced apoptosis in chicken livers, as evidenced by a reduction in the production of NO, iNOS activity, the number of apoptotic cells, and mRNA and protein expression levels of iNOS, caspase-3, Bax, and Cyt-c. It indicated that Cd induced NO-mediated apoptosis through the mitochondrial apoptotic pathway and Se exerted antagonizing effects. The present study provides new insights as to how Se affects Cd-induced toxicity in the chicken liver.

VLDL Induced Modulation of Nitric Oxide Signalling and Cell Redox Homeostasis in HUVEC.

High levels of circulating lipoprotein constitute a risk factor for cardiovascular diseases, and in this context, the specific role of the very-low-density lipoproteins (VLDL) is poorly understood. The response of human umbilical vein endothelial cells (HUVEC) to VLDL exposure was studied, especially focusing on the pathways involved in alteration of redox homeostasis and nitric oxide (NO) bioavailability. The results obtained by the analysis of the expression level of genes implicated in the NO metabolism and oxidative stress response indicated a strong activation of inducible NO synthase (iNOS) upon 24 h exposure to VLDL, particularly if these have been preventively oxidised. Simultaneously, both mRNA and protein expression of endothelial NO synthase (eNOS) were decreased and its phosphorylation pattern, at the key residues Tyr495 and Ser1177, strongly suggested the occurrence of the eNOS uncoupling. The results are consistent with the observed increased production of nitrites and nitrates (NOx), reactive oxygen species (ROS), 3-nitrotyrosine (3-NT), and, at mitochondrial level, a deficit in mitochondrial O2 consumption. Altogether, these data suggest that the VLDL, particularly if oxidised, when allowed to persist in contact with endothelial cells, strongly alter NO bioavailability, affecting redox homeostasis and mitochondrial function.

NO-ergic Control of Blood Circulation in the Medulla Oblongata of Rats with Experimental Hemiparkinsonism under Prolonged Exposure to Continuous Light

The study was conducted on rats with unilateral damage to dopaminergic (DA) neurons in substantia nigra of the midbrain (experimental hemiparkinsonism). Degeneration of dopaminergic (DA) neurons was accompanied by hyperactivity of those neurons that remained intact and responded to apomorphine (Apo) test by rotational movements. Depending on the number of rotations, three groups of animals were defined. In the medulla oblongata of rats with unilateral damage to dopaminergic (DA) neurons, a significant increase in the activity of inducible NO-synthase (iNOS) was observed, while the activity of constitutive NO-synthase (cNOS) tended to decrease compared with that in control rats. An activation of neuronal NOsynthase (nNOS) in those rats by injections of L-arginine in the medullary nuclei was accompanied by weakening the hemodynamic effects compared to those in control rats. An exposure of animals to all-night light for three weeks was accompanied by increasing the number of damaged DA-ergic neurons in substantia nigra. At that, a significant decrease in cNOS activity in the medulla oblongata was observed, leading to the inhibition of de novo synthesis of nitric oxide (NO). The reduction of NO synthesis in the medulla oblongata neurons of rats with experimental hemiparkinsonism following their exposure to continuous light was also evidenced by the reduction of the amount of nitrite (NO2-) anion.

Immunobiology of Nitric Oxide and Regulation of Inducible Nitric Oxide Synthase.

Nitric oxide (NO) is a bioactive gas that has multiple roles in innate and adaptive immune responses. In macrophages, nitric oxide is produced by inducible nitric oxide synthase upon microbial and cytokine stimulation. It is needed for host defense against pathogens and for immune regulation. This review will summarize the role of NO and iNOS in inflammatory and immune responses and will discuss the regulatory mechanisms that control inducible nitric oxide synthase expression and activity.

Hydrogen Sulfide Releasing 2-Mercaptoacrylic Acid-Based Derivative Possesses Cytoprotective Activity in a Small Intestine of Rats with Medication-Induced Enteropathy.

Small intestinal injury is known to be one of the most commonly appearing pathologies, resulting in the use of medications such as: nonsteroidal anti-inflammatory drugs (NSAIDs), antitumor drugs and angiotensin-converting enzyme (ACE) inhibitors. The principal objective of this study is to evaluate the action of a novel mercaptoacrylic acid derivative able to release H2S on parameters of NO-synthase system and oxidative stress. Inducing enteropathy, three types of medications were used: indomethacin, an NSAID (35 mg/kg); methotrexate, an antitumor drug (10 mg/kg); and enalapril, an ACE inhibitor (2 mg/kg/day). 2-[(4-chlorophenyl-carbamoyl)-methyl]-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-acrylic acid (2C3DHTA) was introduced based on the background of medication-induced enteropathy (10 mg/kg/day). The survey showed that malondialdehyde (MDA) concentration, myeloperoxidase (MPO) activity, superoxide dismutase (SOD), catalase, and NO-synthases (NOS) were determined in the small intestinal mucosa. The increase in inducible NO-synthase (iNOS) activity was due to indomethacin and methotrexate administration. Constitutive NO-synthase (cNOS) activity was decreased by an ACE-inhibitor. The cytoprotective effect was demonstrated by 2C3DHTA, which returned iNOS activity to its control level and increased cNOS activity. The enterotoxic action of studied medication was accompanied by the development of oxidative stress manifested, activity of MPO was increased. MPO activity and manifestations of oxidative stress were decreased by 2C3DHTA. Effects of 2C3DHTA can be explained by the action of H2S, released from this compound in the gastrointestinal (GI) system.

Chronic Ethanol Consumption and Thiamine Deficiency Modulate β-Amyloid Peptide Level and Oxidative Stress in the Brain.

Aims The effects of chronic ethanol (EtOH) consumption, associated or not with thiamine deficiency (TD), on β-amyloid peptide (Aβ) level and oxidative stress in the brain were studied in male C57BL/6 mice. Methods Mice were prepared by feeding with an EtOH liquid diet, thiamine-depleted liquid diet and a thiamine-depleted EtOH liquid diet for 7 weeks. Biochemical parameters were measured by corresponding commercial kits. Results EtOH consumption or TD induced a significant decrease in the thiamine level, but induced increased in the β-amyloid peptide 1–42 and β-amyloid peptide 1–40 (Aβ1–40) levels. EtOH consumption led to a significant increase in the malondialdehyde (MDA) and nitric oxide (NO) levels, total nitric oxide synthase (NOS) activities and inducible nitric oxide synthase (iNOS) activities, but a significant decrease in superoxide dismutase (SOD) and glutathione peroxidase activities. TD significantly elevated the MDA content and total NOS and iNOS activities but lowered SOD activity. Aβ1–40 overproduction, the change in the NO level, and SOD activity in the brain induced by chronic EtOH treatment associated with TD were greater than that induced by EtOH or TD alone. Conclusion Findings from this report suggested that chronic EtOH consumption could induce TD, excess Aβ production and oxidative damage, and the association with TD should have more severe effects on the brain. Short summary Chronic EtOH consumption or thiamine deficiency (TD) treatment could reduce the thiamine level, induce β-amyloid peptide (Aβ) overproduction and oxidative stress in the brain. When associated with TD, EtOH consumption caused Aβ overproduction and oxidative damage more serious.

NO-ERGIC CONTROL OF BLOOD CIRCULATION IN THE MEDULLA OBLONGATA OF RATS WITH EXPERIMENTAL HEMIPARKINSONIZM UNDER EXPOSURE TO CONTINUOUS LIGHT.

The study was conducted on rats with unilateral damage to dopaminergic (DA) neurons in substantia nigra of the midbrain (experimental hemiparkinsonism). Degeneration of dopaminergic (DA) neurons was accompanied by hyperactivity of those neurons that remained intact and responded to apomorphine (Apo) test by rotational movements. Depending on the number of rotations, three groups of animals were defined. In the medulla oblongata of rats with unilateral damage to dopaminergic (DA) neurons, a significant increase in the activity of inducible NO-synthase (iNOS) was observed, while the activity of constitutive NO-synthase (cNOS) tended to decrease compared with that in control rats. An activation of neuronal NO-synthase (nNOS) in those rats by injections of L-arginine in the medullary nuclei was accompanied by weakening of the hemodynamic effects compared to those in control rats. An exposure of animals to continuous light for three weeks was accompanied by increasing the number of damaged DA-ergic neurons in substantia nigra. At that, a significant decrease in cNOS activity in the medulla oblongata was observed, leading to the inhibition of de novo synthesis of nitric oxide (NO). The reduction of NO synthesis in the medulla oblongata neurons of rats with experimental hemiparkinsonism following their exposure to continuous light was also evidenced by the reduction.

Porcine glucagon-like peptide-2 microspheres ameliorate inflammation in lipopolysaccharide-challenged weaning piglets.

This study aimed to investigate the effects of porcine [gly2] glucagon-like peptide-2 (p[gly2]GLP-2) microspheres on lipopolysaccharide-challenged piglets and to evaluate efficacy of microspheres for administration compared with more conventional administration. Eighteen 21-d-old Duroc female piglets were randomly assigned into 3 groups: the control group (intraperitoneal injection with 3 mL saline solution daily), the glucagon-like peptide-2 (GLP-2) group (intraperitoneal injection with 3 mL p[gly2]GLP-2 at 20 nmol/kg BW daily), and the microsphere (MS) group (intraperitoneal injection with 100 mg p[gly2]GLP-2 microsphere suspension at Day 1). On Day 8, all piglets were injected with 100 μg lipopolysaccharide/kg BW. Results showed that administration of p[gly2]GLP-2 microspheres decreased the -lactic acid and methane dicarboxylic aldehyde content of the serum and increased the villus height and villus crypt ratio in the duodenum and ileum. Inducible nitric oxide synthase activity in the duodenum and ileum decreased, whereas enzyme activity for sucrose and Na-K adenosine triphosphatase in the ileum increased with treatment of p[gly2]GLP-2 microspheres. In the MS group, we observed downregulation of IL-8, TNF-α, IFN-γ, and GLP-2R mRNA expression in the ileum, upregulation of positive cell expression in the duodenum and positive cell expression in the ileum, and downregulation of GLP-2 receptor positive cell expression in the ileum. One injection of p[gly2]GLP-2 microspheres was as effective as p[gly2]GLP-2 administered for 7 d. Results suggested that p[gly2]GLP-2 can be a candidate agent for ameliorating weaning stress in piglets and that the use of microspheres is an ideal delivery system for GLP-2.

Is there a role of inducible nitric oxide synthase activation in the delayed antiarrhythmic effect of sodium nitrite?

This study aimed to examine whether inducible nitric oxide synthase (iNOS) plays a role in the delayed antiarrhythmic effect of sodium nitrite. Twenty-one dogs were infused intravenously with sodium nitrite (0.2 μmol·kg-1·min-1) for 20 min, either in the absence (n = 12) or in the presence of the iNOS inhibitor S-(2-aminoethyl)-isothiourea (AEST) (total dose 2.0 mg·kg-1 i.v., n = 9). Control dogs (n = 12) were given saline. Twenty-four hours later, all of the dogs were subjected to a 25 min period occlusion of the left anterior descending coronary artery followed by rapid reperfusion. Dogs treated with AEST and nitrite received again AEST prior to the occlusion. Compared with the controls, sodium nitrite markedly reduced the number of ectopic beats, the number and incidence of ventricular tachycardia, and the incidence of ventricular fibrillation during occlusion and increased survival (0% versus 50%) from the combined ischaemia and reperfusion insult. Although AEST completely inhibited iNOS activity, the nitrite-induced increase in NO bioavailability during occlusion was not substantially modified. Furthermore, AEST attenuated but did not completely abolish the antiarrhythmic effect of nitrite. The marked delayed antiarrhythmic effect of sodium nitrite is not entirely due to the activation of iNOS; other mechanisms may certainly play a role.

Low-Dose-Rate Irradiation for 1 Hour Induces Protection Against Lethal Radiation Doses but Does Not Affect Life Span of DBA/2 Mice.

Prior findings showed that serum from DBA/2 mice that had been given whole-body irradiation for 1 hour at a low dose rate (LDR) of 30 cGy/h induced protection against radiation in reporter cells by a mechanism depending on transforming growth factor β3 and inducible nitric oxide synthase activity. In the present study, the effect of the 1 hour of LDR irradiation on the response of the preirradiated mice to a subsequent lethal dose and on the life span is examined. These DBA/2 mice were prime irradiated for 1 hour at 30 cGy/h. Two experiments with 9 and 9.5 Gy challenge doses given 6 weeks after priming showed increased survival in primed mice compared to unprimed mice followed up to 225 and 81 days after challenge irradiation, respectively. There was no overall significant difference in life span between primed and unprimed mice when no challenge irradiation was given. The males seemed to have a slight increase in lifespan after priming while the opposite was seen for the females.

Effects of dietary arginine and glutamine on growth performance, nonspecific immunity, and disease resistance in relation to arginine catabolism in juvenile turbot (Scophthalmus maximus L.)

A 12-week feeding trial was conducted to investigate the effects of dietary arginine (Arg), glutamine (Gln), and their interactions on growth performance, nonspecific immunity, disease resistance, and Arg catabolism in juvenile turbot (Scophthalmus maximus L.). The basal diet was formulated with white fish meal, soybean meal, and corn gluten meal to contain 50% crude protein and 12% crude lipid. Nine isoproteic and isolipidic experimental diets were formulated by supplementing the basal diet with three levels of l-Arg and l-Gln (0.0%, 1.0%, and 2.0% each). Triplicate groups of 35 fish were fed a fixed ration twice daily in an indoor recirculating seawater system. After the feeding trial, fish were challenged by Edwardsiella tarda and survival rate (SR) was recorded for 7days. The results showed that dietary Arg and Gln levels did not significantly affect growth performance of juvenile turbot (P>0.05). Respiratory burst activity in head-kidney macrophages increased significantly as dietary Arg or Gln increased (P<0.05), but no significant interactions was observed (P>0.05). Significant interactions between dietary Arg and Gln were observed on lysozyme and glutathione peroxidase activity in serum (P<0.05). There was also a significant interactive effect of dietary Arg and Gln on inducible nitric oxide synthase activity in serum and liver, and arginase I gene expression in liver (P<0.05). Fish fed diets with the highest Arg and Gln showed significantly higher levels of arginase I gene expression in liver (P<0.05). After the E. tarda challenge, SR of juvenile turbot were significantly improved as dietary Arg increased (P<0.05), but no significant effect of dietary Gln and their interactions was observed (P>0.05). It can be concluded that inclusion of Arg and Gln in the diet did not have a positive effect on growth performance of juvenile turbot, but significantly improved nonspecific immune responses. Dietary Arg and Gln levels also had significantly interactive effects on Arg catabolism. Disease resistance was significantly enhanced with the increasing of dietary Arg.