ABSTRACT
In the present study, in order to reveal novel adverse effects of ultrafine particles (UFP) on the central nervous system, the effects of nanoparticle-rich diesel exhaust particles (NRDEP; count mode diameter, 21.45 nm) on emotional behavior, learning capability and brain neurotransmitter levels were studied in rats by intranasal instillation (iNI). NRDEP (10 and 50 µg/rat) was instilled into 2-week old infant, male rats once a week for 4 weeks. Spontaneous motor activity measured was observed to be inverse to the dose level. In active avoidance tests using a shuttle box, NRDEP-treated animals showed a lower avoidance performance than control animals given air-instillation. The levels of dopamine and its metabolite (DOPAC) in the medial mammillary nucleus of the brain tended to be lower in the NRDEP-treated animals. From these results, although the effects of NRDEP by iNI on the emotionality and the brain neurotransmitter levels were not fully clear, the results obtained by avoidance testing suggested involvement of UFP in learning capability.
Subject(s)
Air Pollutants/toxicity , Avoidance Learning/drug effects , Behavior, Animal/drug effects , Brain/drug effects , Nanoparticles/toxicity , Vehicle Emissions/toxicity , 3,4-Dihydroxyphenylacetic Acid/metabolism , Administration, Intranasal , Animals , Animals, Suckling , Brain/metabolism , Brain/physiopathology , Dopamine/metabolism , Motor Activity/drug effects , RatsABSTRACT
The influences of inhaling particulate air-pollutants on hematopoiesis and myocardial oxidative stress were investigated in mice by intratracheal instillation (IT) of diesel exhaust particles (DEP), its dichloromethane soluble-component (DMSC) or residual particle-component (RPC). After IT, time courses of cytokine levels in bronchial alveolar lavage fluid (BALF), peripheral blood cell count, myocardial myeloperoxidase (MPO) activity and myocardial chemokine levels were observed for 24 hr. RPC caused sustained blood neutrophilia while that caused by DEP and DMSC was transient. RPC also caused sustained elevations of granulocyte colony-stimulating factor (G-CSF) and interleukin (IL)-6 levels in BALF. Furthermore, IL-1beta level in BALF in the RPC group was significantly elevated at 24 hr after IT. Significant positive correlations were observed between blood neutrophil count and IL-6/G-CSF levels in BALF. MPO activity in the myocardium was increased by RPC at 12 and 24 hr after IT while the activities in the kidney and the liver were not affected. Significant correlation was also observed between myocardial MPO activity and blood neutrophil count at 12 hr after IT, for all three substances. From these results, it was concluded that particle component of DEP may enhance myocardial oxidative stress via blood neutrophilia and the elevation of cytokine levels in BALF.
Subject(s)
Myocardium/metabolism , Neutrophil Infiltration/drug effects , Neutrophils/drug effects , Oxidative Stress/drug effects , Particulate Matter/toxicity , Pneumonia , Trachea/drug effects , Vehicle Emissions/toxicity , Animals , Bronchoalveolar Lavage Fluid/cytology , Bronchoalveolar Lavage Fluid/immunology , Cytokines/immunology , Inhalation Exposure/adverse effects , Kidney/drug effects , Kidney/immunology , Leukocyte Count , Liver/drug effects , Liver/immunology , Male , Mice , Mice, Inbred Strains , Myocardium/enzymology , Myocardium/immunology , Neutrophil Infiltration/immunology , Neutrophils/cytology , Neutrophils/immunology , Oxidative Stress/immunology , Peroxidase/metabolism , Pneumonia/blood , Pneumonia/chemically induced , Pneumonia/immunologyABSTRACT
Since our previous study demonstrated the exacerbation of acute myocardial ischemia/reperfusion (AMIR)-related arrhythmia by intratracheal instillation (IT) of diesel exhaust particles (DEP), the influence of IT with extracts of DEP in organic solvents on AMIR-related arrhythmia was examined in rats. Oxidative activity in a non-biological assay system and proinflammatory activity in mice of DEP extracts were examined. The dichloromethane-soluble fraction (DMSF) of DEP was further fractionated into n-hexane-soluble (n-HSF) and n-hexane-insoluble (n-HISF) fractions. The oxidative activities of the fractions evaluated by dithiothreitol assay were ranked as follows: n-HISF>DMSF>n-HSF. Twenty-one to 34 hr after IT, the AMIR experiment was performed. Exacerbation of AMIR-related arrhythmia and increased reperfusion-related mortality were observed only in rats treated with DMSF. In fact, n-HSF and n-HISF did not affect arrhythmia up to 5 mg/kg. Twelve hr after IT, a significant increase in neutrophil count was observed only with DMSF. The levels of granulocyte colony-stimulating factor and interleukin-6 in bronchoalveolar lavage fluid were significantly elevated in the group treated with DMSF, while neither, n-HSF nor n-HISF, affected the level of cytokines up to 5 mg/kg. In fact, tumor necrosis factor-alpha, IL-10 and granulocyte-macrophage colony-stimulating factor were unchanged with any of the fractions. In conclusion, exacerbation of AMIR-related arrhythmia by DMSF suggests the contribution of non-particle components of DEP to arrhythmia while the component contributed to the effects did not become clear. Furthermore, it is confirmed that exacerbation of AMIR-related arrhythmia is accompanied by an increased neutrophil count in the circulatory blood.
Subject(s)
Air Pollutants/toxicity , Arrhythmias, Cardiac/immunology , Lung Diseases/immunology , Reperfusion Injury/complications , Vehicle Emissions/toxicity , Air Pollutants/chemistry , Animals , Arrhythmias, Cardiac/etiology , Bronchoalveolar Lavage Fluid/immunology , Complex Mixtures/chemistry , Complex Mixtures/toxicity , Cytokines/immunology , Hexanes/chemistry , Inflammation/etiology , Inflammation/immunology , Leukocyte Count , Lung Diseases/etiology , Male , Methylene Chloride/chemistry , Mice , Mice, Inbred Strains , Neutrophils/immunology , Oxidation-Reduction , Rats , Rats, Sprague-Dawley , Reperfusion Injury/immunology , Solvents/chemistryABSTRACT
We have previously demonstrated that intratracheal instillation (IT) with diesel exhaust particles (DEP) exacerbates myocardial ischemia/reperfusion-induced arrhythmia in rats. Since activated neutrophils play a pivotal role in ischemia/reperfusion arrhythmia, in the present study we investigated the effects of DEP on peripheral neutrophil count and on the oxyradical production (ORP) of neutrophils in rats. We also determined the production of cytokines for better understanding of the relationship between pulmonary inflammation and neutrophil function. Instillation with 5 mg DEP elevated circulatory neutrophil counts (CNC) at 12 and 24 h post-instillation to levels approximately 2.1- and 2.3-fold those in the vehicle-treated animals, respectively. On the other hand, 1-mg DEP caused an approximately 0.4-fold increase in CNC at 6 h. 12-O-Tetradecanoylphorbol 13-acetate-induced ORP in the isolated neutrophil was enhanced at 12 and 24 h after instillation with 5 mg DEP. Cytokine-induced neutrophil chemoattractant-1 (CINC-1), tumor necrosis factor-alpha (TNFalpha) and macrophage inflammatory protein-2 (MIP-2) levels were increased in the bronchoalveolar lavage fluid (BALF) collected from animals that received 5 mg DEP. In serum, a marked elevation of CINC-1 and a slight elevation of MIP-2 were also observed, while TNFalpha was not detected. Granulocyte-macrophage colony-stimulating factor (GM-CSF) was detected in neither BALF nor serum for 24 h after the instillation. These results suggest that IT instillation of DEP enhances systemic oxidative stress by increasing neutrophil count and ORP in the acute period.
Subject(s)
Air Pollutants/toxicity , Neutrophils/metabolism , Reactive Oxygen Species/metabolism , Vehicle Emissions/toxicity , Animals , Bronchoalveolar Lavage Fluid/chemistry , Bronchoalveolar Lavage Fluid/cytology , Bronchoalveolar Lavage Fluid/immunology , Cell Count , Chemokine CXCL1 , Chemokine CXCL2 , Chemokines, CXC/blood , Chemokines, CXC/metabolism , Intercellular Signaling Peptides and Proteins/blood , Intercellular Signaling Peptides and Proteins/metabolism , Intubation, Intratracheal , Male , Neutrophils/drug effects , Neutrophils/immunology , Rats , Rats, Sprague-Dawley , Time Factors , Tumor Necrosis Factor-alpha/metabolismABSTRACT
For understanding the relationship between the increased incidence of sudden cardiac death and air pollution, we examined the effects of intratracheal instillation of diesel exhaust particles (DEP) on acute myocardial ischemia/reperfusion-induced arrhythmia in rats. The animals received 1 mg DEP 24-48 h before the ischemia/reperfusion (DEP-pretreated group, DEP-PRE), and were subjected to 3 successive brief ischemia/reperfusion (3 min ischemia followed by 5 min reperfusion) procedures. These were to make the animals tolerant to ischemia/reperfusion-related myocardial deterioration. Thereafter the animals were subjected to a 10-min ischemia followed by a 30-min reperfusion. In the experiments, an increased mortality was observed in the DEP-PRE group compared to the vehicle (0.05% Tween 80-PBS)-treated group. Forty-six percent of the animals in DEP-PRE died during the first 3-min reperfusion period. The animals of other groups were intratracheally instilled with DEP at the beginning of ischemia/reperfusion experiment, or were pretreated with polyethylene glycol-conjugated superoxide dismutase (1000 IU kg(-1), iv). In these animals, incidences of both arrhythmia and mortality were similar to those in the animals treated with the vehicle. In experiments to investigate the effects of DEP on the biochemical and hematological parameters, neutrophil count was elevated by a higher dose (5 mg) of DEP at 24 h after the intratracheal instillation, and oxygen radical production, which was induced by 12-O-tetradecanoylphorbol 13-acetate, was enhanced at 72 h. These results indicate that intratracheal DEP instillation exacerbates short-period ischemia/reperfusion-induced arrhythmia. Delivery and activation of peripheral neutrophils and oxygen radicals produced in neutrophils might participate in this exacerbation. This is the first article that demonstrates the arrhythmogenicity of DEP using intratracheal instillation in rats.
