Macrophage activation by polysaccharides from Atractylodes macrocephala Koidz through the nuclear factor-κB pathway

Abstract

Context: Atractylodes macrocephala Koidz is a traditional herb. Atractylodes macrocephalaon polysaccharides (AMP) have been found to enhance immunity and improve heart function. However, the mechanisms of the immunomodulatory effect have not been investigated.

Objective: We examined whether AMP activated macrophages and explored the mechanisms of activation.

Materials and methods: AMP was prepared and evaluated its immunomodulatory activity (25, 50, 100, and 200?μg/mL) by detecting the phagocytosis and the production of tumor necrosis factor-α (TNF-α), IFN-γ, and nitric oxide (NO) in RAW264.7 macrophages. Furthermore, the role of nuclear factor-κB (NF-κB) pathway was examined in regulating TNF-α and NO production.

Results: The phagocytosis of macrophages was enhanced by AMP in a dose-dependent manner and the maximal phagocytosis of macrophages occurred at concentrations of 100 and 200?μg/mL. NO, TNF-α, and IFN-γ release was also found to be dose dependent by increasing concentrations of AMP and reached the peak at a concentration of 200?μg/mL. In addition, AMP induced inhibitor kappaB (IκB) degradation and the activation of NF-κB by p65 nuclear translocation, and then the activation of NF-κB in nucleus peaked at a concentration of 200?μg/mL. Besides, NF-κB-specific inhibitor pyrrolidine dithiocarbamate (PDTC) decreased AMP-induced NO and TNF-α production.

Discussion and conclusion: These data suggest that AMP may modulate macrophage activities by stimulating NF-κB or activating NF-κB-dependent mechanisms.     

Artin M enhances TNF-α production and phagocytosis of Candida albicans mediated by dectin-1 and mannose receptors

The activities of dectin-1 and mannose receptors on phagocytosis of Candida albicans and the production of TNF-α by macrophages from mice pretreated for 3 days with extract of Artocarpus intergrifolia seeds (jack extract), Artin M or jacalin were studied. Macrophages from these mice were coincubated with C. albicans CR15 (yeast), in the presence of mannose (50mM) plus mannan (100 μg) or laminarin (1mg). Phagocytosis was significantly enhanced to 52% in macrophages from mice pretreated intraperitoneally for 3 days with jack extract (500 μg/250 μl PBS). Reduction in phagocytosis from 52% to 34% (P<0.05) occurred in the presence of mannose receptor inhibitors and from 52% to 16% (P<0.01) in the presence of dectin-1 inhibitor laminarin, whereas only 20% of control macrophages phagocytosed blastoconidia. Similar results were verified for pretreatment of mice with Artin M (2.5 μg/250 μl PBS), but not for jacalin (25 μg/250 μl PBS). Macrophages from mice pretreated 3 days previously with jack extract or Artin M and then coincubated for 2h with C. albicans presented a significant increase in TNF-α production, correlating with significantly less transition of yeast to filamentous forms compared to pretreatment with jacalin. These results suggest that Artin M, but not jacalin present in jack extract significantly increased TNF-α production and the activity of mannose and dectin-1 receptors.     

Psilostachyin C: a natural compound with trypanocidal activity

In this study, the antiprotozoal activity of the sesquiterpene lactone psilostachyin C was investigated. This natural compound was isolated from Ambrosia scabra by bioassay-guided fractionation and was identified by spectroscopic techniques. Psilostachyin C exerted in vitro trypanocidal activity against Trypanosoma cruzi epimastigotes, trypomastigotes and amastigotes, with 50% inhibitory concentration (IC(50)) values of 0.6, 3.5 and 0.9 μg/mL, respectively, and displayed less cytotoxicity against mammalian cells, with a 50% cytotoxic concentration (CC(50)) of 87.5 μg/mL. Interestingly, this compound induced ultrastructural alterations, as seen by transmission electron microscopy, in which vacuolisation and a structural appearance resembling multivesicular bodies were observed even at a concentration as low as 0.2 μg/mL. In an in vivo assay, a significant reduction in the number of circulating parasites was found in T. cruzi-infected mice treated with psilostachyin C for 5 days compared with untreated mice (7.4 ± 1.2 × 10(5)parasites/mL vs. 12.8 ± 2.0 × 10(5)parasites/mL) at the peak of parasitaemia. According to these results, psilostachyin C may be considered a promising template for the design of novel trypanocidal agents. In addition, psilostachyin C inhibited the growth of Leishmania mexicana and Leishmania amazonensis promastigotes (IC(50)=1.2 μg/mL and 1.5 μg/mL, respectively).     

Effect of cysteine ethylester hydrochloride (Cystanin) on host defense mechanism (IV): Potentiating effects on the function of peritoneal or spleen macrophages

L-Cysteine ethylester hydrochloride (ethylcysteine; 30 mg/kg, p.o.) increased the number of la-positive cells (antigen presenting cells) in spleen adherent cells (SAC) and that of Lyt 1.2-positive cells (helper T cells), but not that of Lyt 2.2-positive cells (suppressor T cells) of C57BL/6 mice immunized with sheep red blood cells. The production of hemolytic plaque forming cells (HPFC) in spleens of syngeneic recipient mice was enhanced by the transfer of SAC or spleen lymphocytes of the donor mice pretreated with ethylcysteine. This drug augmented phagocytosis of yeast particles by peritoneal macrophages of ICR mice at concentrations of 1-100 microM. In ex vivo experiments, this drug (30 mg/kg, p.o.) augmented the phagocytosis of yeast particles by mouse macrophages and showed a tendency to increase the macrophage number in the peritoneal cavity. Ethylcysteine (30 mg/kg, p.o.) significantly accelerated the decrease of viable E. coli number in the liver of normal mice 2 and 48 hr after challenge. Furthermore, this drug at the same dose restored the suppression of the decrease of E. coli number in the blood and liver of mice treated with cyclophosphamide (200 mg/kg, i.p.). These results suggest that ethylcysteine augments the functions of macrophages in vitro and ex vivo, and these enhancing effects may lead to the enhancement of host resistance to infections in compromised hosts.     

Investigating the function of a novel protein from Anoectochilus formosanus which induced macrophage differentiation through TLR4-mediated NF-κB activation

Anoectochilus formosanus is a therapeutic orchid appreciated as a traditional Chinese medicine in Asia. The extracts of A. formosanus have been reported to possess hepatoprotective, anti-inflammatory, and anti-tumor activates. A novel protein was isolated from A. formosanus, and its immunomodulatory effect on murine peritoneal macrophage was investigated. Macrophages obtained from ascites of thioglycollate-induced BALB/c were co-cultured with IPAF (0-20 μg/ml) for 24 h and then harvested for flow cytometry analysis. The cytokine/chemokine production was measured by real time PCR and ELISA. The interaction between IPAF and toll like receptors (TLRs) was investigated by TLR gene knockout (KO) mice and fluorescence labeled IPAF. The activation of NF-κB was assessed by EMSA. IPAF stimulated the TNF-α and IL-1β production, upregulated the CD86 and MHC II expression, and enhanced the phagocytic activity of macrophages. IPAF induced gene expression of IL-12 and Th1-assosiated cytokines/chemokines. The stimulating effect of IPAF was impaired, and the IPAF-macrophage interaction was reduced in TLR4(-/-) C57BL/10ScNJ mice. In addition, IPAF stimulated expressions of TLR signal-related genes and the activation of NF-κB. IPAF could induce classical activated macrophage differentiation via TLR4-dependent NF-κB activation and had potential of IPAF to modulate the Th1 response. These findings provided valuable information regarding the immune modulatory mechanism of A. formosanus, and indicated the possibility of IPAF as a potential peptide drug.     

Macrophage immunomodulatory activity of polysaccharides isolated from Glycyrrhiza uralensis Fish

The objective of this study was to evaluate the immunomodulatory effects of the purified glycyrrhiza polysaccharides (GP) on the activity of macrophages. A purified fraction of water-soluble polysaccharides, with estimated molecular weight of 10 kDa, was isolated from Glycyrrhiza uralensis Fish using ion exchange and size exclusion chromatography. The results indicate that GP increased the pinocytic activity, the production of nitric oxide (NO), interleukin-1 (IL-1), IL-6 and IL-12 in a dose-dependent manner. The production of IL-1 was induced by GP at a dose of 10 microg/mL; but, NO, IL-6 and IL-12 was significantly induced at 100 microg/mL. A time-dependent enhancement showed that the production of IL-1, NO and IL-12 were significantly increased within 6 h. Superoxide anion (O(2)(-)) production by macrophages from GP-treated mice was higher than that of cells from untreated mice. Moreover, cells from both untreated and treated mice responded to phorbol 12-myristate 13-acetate (PMA) treatment; however, the O(2)(-) production was higher in the cells from treated mice than that of cells from untreated mice. Our data suggest that the beneficial therapeutic effects of GP may be attributed partly to its ability to modulate macrophage immune functions.     

M2型巨噬细胞外泌体对小鼠自身免疫性肝炎的保护作用#br#

摘要：目的　探究M2型巨噬细胞来源的外泌体（M2 Exos）对刀豆蛋白A（Con A）诱导的小鼠自身免疫性肝炎（AIH）的保护作用。方法　采用IL-4（20 μg/L）刺激RAW264.7巨噬细胞24 h后提取M2 Exos并用透射电子显微镜、纳米颗粒跟踪分析技术和蛋白质免疫印迹对其进行鉴定;免疫荧光观察RAW264.7巨噬细胞对M2 Exos的摄取情况。将12只C57BL/6J小鼠随机分为PBS组、DiR-M0 Exos组、DiR-M2 Exos组和DiR染料对照组。Con A（15 mg/kg）注射完成1 h后通过尾静脉分组注射PBS溶液、DiR-M0 Exos（100 μg）、DiR-M2 Exos（100 μg）和DiR染料,活体成像技术观察Exos在AIH小鼠肝、脾、心、肺、肾、肠的分布情况。将20只C57BL/6J小鼠随机分为Control组（PBS溶液）、Con A组（15 mg/kg Con A）,M0 Exos组（15 mg/kg Con A+200 μg M0 Exos）和M2 Exos组（15 mg/kg Con A+200 μg M2 Exos）,每组5只。Con A注射完成12 h后处死小鼠,收集外周血和肝组织,全自动生化仪测定血清丙氨酸转氨酶（ALT）和天冬氨酸转氨酶（AST）水平;苏木精-伊红（HE）染色观察肝脏病理形态变化;实时荧光定量PCR（qPCR）检测肝组织肿瘤坏死因子（TNF）-α和白细胞介素（IL）-6的mRNA表达水平;流式细胞术检测肝脏巨噬细胞亚群变化情况。结果　成功诱导并分离了M2 Exos,可被RAW264.7巨噬细胞摄取;经尾静脉注射后,M2 Exos主要在小鼠肝脏和脾脏中蓄积。与Control组相比,Con A组小鼠血清ALT和AST明显升高（P＜0.05）,肝脏结构紊乱,肝细胞大片坏死,肝组织TNF-α和IL-6 mRNA表达升高（P＜0.05）,肝脏单核细胞来源巨噬细胞（MoMFs）的浸润增多（P＜0.05）。与Con A组相比,M2 Exos组小鼠血清ALT和AST水平显著下降（P＜0.05）,肝脏坏死明显减轻,肝组织TNF-α和IL-6 mRNA表达降低（P＜0.05）,肝脏MoMFs的浸润减少（P＜0.05）。结论　M2 Exos可对小鼠AIH起到保护作用,其作用机制可能与降低肝脏炎性细胞因子的表达及减少对MoMFs的招募有关。     

Alteration of immune functions and Th1/Th2 cytokine balance in nicotine-induced murine macrophages: immunomodulatory role of eugenol and N-acetylcysteine

The aim of this study was to evaluate the immune functions by nicotine-induced murine peritoneal macrophages, and Th1/Th2 cytokine balance in it, and concurrently to establish the immunomodulatory role of eugenol, and N-acetylcysteine in nicotine-induced macrophages. Eugenol was isolated from Ocimum gratissimum, and characterized by HPLC, FTIR, and (1)H NMR. The cytotoxic effect of isolated eugenol was studied in murine peritoneal macrophages at various concentrations (0.1-50 μg/ml) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. To evaluate the immunomodulatory role of eugenol and N-acetylcysteine, ROS and nitrite generations, phenotype functions by macrophages were studied. The effect of eugenol and N-acetylcysteine on the release of Th1 cytokines (TNF-α, IL-12) and Th2 cytokines (IL-10, TGF-β) was measured by ELISA, and the expression of these cytokines at mRNA level were analyzed by real-time PCR. Eugenol, at a dose of 15 μg/ml, showed less cytotoxicity to the macrophages and it significantly reduced the nicotine-induced ROS, NO generation, and iNOSII expression. Similar kinds of response were observed in the presence of N-acetylcysteine (1 μg/ml). We have found the decreased adherence, chemotaxis, phagocytosis and intracellular killing of bacteria in nicotine treated macrophages, whereas eugenol and N-acetylcysteine with nicotine treatment enhanced these cellular functions by macrophages significantly (p < 0.05). Eugenol and N-acetylcysteine were found to down regulate the Th1 cytokines in nicotine treated macrophages with concurrent activation of Th2 responses. These findings strongly enhanced our understanding of the molecular mechanism leading to nicotine-induced suppression of immune functions, and provide additional rationale for the application of anti-inflammatory therapeutic approaches by eugenol, and N-acetylcysteine for different inflammatory diseases prevention and treatment during nicotine toxicity.     

Activation of macrophages by polysaccharide isolated from Paecilomyces cicadae through toll-like receptor 4

Paecilomyces cicadae have been reported to have immunomodulatory properties. In this study, we investigated the effect of polysaccharide (PCP) isolated from P. cicadae on the macrophages. PCP increased the production of nitric oxide (NO) and the gene expression of IL-1β, IL-6, and TNF-α in RAW 264.7 cells. To investigate the membrane receptor, we examined the effect of PCP on primary macrophages isolated from wild type C3H/HeN and C3H/HeJ mice having mutant-TLR4. PCP induced NO production and cytokine gene expression in macrophages from C3H/HeN, but not from tlr4-mutated C3H/HeJ mice, which suggests that TLR4 is the membrane receptor for PCP. PCP induced the phosphorylation of ERK, JNK, and p38, and the nuclear translocation of NF-κB p50/p65, which are the main signaling molecules downstream from TLR4. Among them, p38 and NF-κB signaling played a crucial role in PCP-induced NO production by macrophages. These results indicate that PCP activates macrophages through the TLR4 signaling pathway.     

Extract from <Emphasis Type="Italic">Calotropis procera</Emphasis> latex activates murine macrophages

Calotropis procera latex has long been used in traditional medicines. Extracts from C. procera latex have been reported to have various pharmacological actions, including protection from myocardial infarction, hepatoprotective action, antitumor activity, antinociceptive, and pro- and anti-inflammatory actions. To evaluate the immunomodulatory functions of the water-soluble C. procera extract (CPE), we investigated its ability to activate macrophages—effector cells in inflammatory and immune responses. Intraperitoneal injection of CPE in mice (2 mg/mouse) induced migration of macrophages to the intraperitoneal cavity, confirming the proinflammatory effects of water-soluble CPE. The direct effects of CPE on macrophages were then assessed by measuring the production of nitric oxide (NO) as an indicator for macrophage activation. Addition of CPE (1–10 μg/ml) to the culture medium of the murine monocyte/macrophage cell line RAW264.7 caused an increase in NO production in a time- and dose-dependent manner. CPE-elicited NO production was blocked by application of an inhibitor of inducible nitric oxide synthase (iNOS). Expression of iNOS mRNA was induced by treatment of cultured macrophages with CPE. Injection of CPE in mice also resulted in an increase in plasma NO level. The results suggest that CPE activates macrophages and facilitates NO production via up-regulation of iNOS gene expression. A. l. S. Seddek and M. Elsayed Mahmoud contributed equally to this work.     

Genetic variation in in-vitro cytokine-induced production of nitric oxide by murine peritoneal macrophages

Quantitative aspects of the in-vitro interferon (IFN)-gamma-induced nitric oxide (NO) production by peritoneal macrophages of eight inbred strains of mice were investigated. Animals employed in the study can be assorted into three phenotype categories: high, moderate, and low NO-responders. Concentration of nitrites in the 24-h supernatants of cells stimulated with recombinant murine IFN-gamma (25 U/ml) reached the following values (mean +/- SEM; in microM): C57BL/10 (33.7+/-1.88) = C57BL/6 (32.1+/-2.10) > SIL (24.0+/-1.55) > CBA/J (18.1+/-1.79) = C3H/HeN (18.0+/-1.10) > DBA/2 (11.4+/-1.16) = DBA/1 (11.0+/-1.20) = Balb/c (11.0+/-1.16). Approximately 80% of the total variation was found to be controlled by genetic factors. No association between the extent of NO formation and variation in the constitutive expression of macrophage IFN-gamma receptor was observed. Similar magnitude of inter-strain differences was sustained after enhanced NO-stimulation of the cells with IFN-gamma + tumour necrosis factor (TNF)-alpha, but only high (strains BL/10, BL/6, SJL, CBA/J, C3H/HeN) and low (DBA/1, DBA/2, Balb/c) NO-responder phenotypes were detected after the triple cytokine cocktail composed of IFN-gamma + TNF-alpha + interleukin (IL)-10. The strain differences remained unchanged after the supplementation of culture medium with L-arginine or tetrahydrobipopterin. Genetically governed differences in IFN-gamma-induced NO production have been found to be tightly associated with differential expression of inducible nitric oxide synthase mRNA. Possible implications of the findings for various fields of NO biomedical research are discussed.     

Anti-infective activities of Pelargonium sidoides (EPS® 7630): effects of induced NO production on Leishmania major in infected macrophages and antiviral effects as assessed in a fibroblast-virus protection assay

EPs? 7630 is an aqueous-ethanolic extract of the roots of Pelargonium sidoides, employed in the treatment of upper respiratory tract infections. Its anti-infective activity is supposed to be associated with the activation of the nonspecific immune system. Using Leishmania major GFP-infected murine BMMΦ, the NO production of EPs? 7630-activated macrophages was correlated with the reduction of the GFP signal measured at single cell levels using flow cytometry. The anti-infectious effect of EPs? 7630 (3-10 μg/mL) on its own (NO production: 4-13 μM; signal reduction: 25-73 %) was less prominent than that in combination with IFN- γ (100 U/mL) (NO production: 20-27 μM; signal reduction: 35-78?%). Furthermore, supernatants of EPs? 7630-stimulated BMMΦ (10 μg/mL) significantly reduced the cytopathic effect of EMCV on L929 fibroblasts (antiviral activity 80 U/mL) when compared with an IFN- γ standard (100 U/mL). Direct addition of EPs? 7630 to L929 did not mediate cytoprotective effects. The antiviral components induced in BMMΦ by EPs? 7630 remain to be identified. Detection of any IFNs by ELISA was unsuccessful, which may be due to their very low concentrations in cell supernatants. The current data provide convincing support for the induction of anti-infectious responses by EPs? 7630.     

Mechanism of antiviral action of quercetin against cardiovirus infection in mice

Oral treatment with quercetin protected ABD2F1/Jena mice significantly against intraperitoneal encephalomyocarditis, Col, SK, MM, Mengo M,L and MengoM virus infections, but not against intracerebral challenge with MengoM virus. Enhanced resistance to MengoM virus were induced in the genetically different DBA 2/Jena, C57BL/Jena, C57BL/Lati and ABC2F1/Jena mice, C57BL6/Jena nu/nu mice were also protected, indicating that the thymus was non-essential to the protective effects of quercetin. In AB/Jena and Lati:CFLP mice the drug failed to be effective. Quercetin was not virucidal and did not interfere with Mengo virus replication in L cells. Interferon was not detected (less than 1 : 8) in sera of ABD2F1/Jena mice 1-48 h after oral administration of the drug. The virus spread from the site of injection to the lymph nodes and other target organs were impaired. Silica treatment, to suppress macrophage function, did not evidently increase the susceptibility of ABC2F1/Jena mice to Mengo virus. However, this treatment abolished the antiviral activity of quercetin, indicating the requirement for macrophages for quercetin to be effective. Virus replication could not be demonstrated in cultures of adherent peritoneal macrophages from either untreated or quercetin-treated ABD2F1/Jena mice.     

Hepatic toxicity and uroporphyrinogen decarboxylase activity following a single dose of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin to mice

A single, low-lethality, oral dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (75 μg/kg) induces an hepatic porphyria in C57BL/10 mice of either sex. The hepatic porphyrin levels are maximal 4–6 weeks after dosing and are still elevated 12 weeks after the dose. The activity of hepatic uroporphyrinogen decarboxylase is depressed within one week of the dose and this appears to precede the onset of porphyria. Mice of the DBA/2 strain show no changes of the same magnitude at doses of 1200 μg/kg, for porphyrin levels, or 75 μg/kg, for decarboxylase activity. In both strains there is an increase in hepatic iron content 3 weeks after the 75 μg/kg dose. Female C57BL/10 mice are more resistant than males to the lethal effects of TCDD.     

Enhanced acquisition of cocaine self-administration by increasing percentages of C57BL/6J genes in mice with a nonpreferring outbred background

Rationale Individual differences in the propensity to acquire drug self-administration may have a substantial genetic basis.Objectives To study the genetic contribution to cocaine self-administration by comparing hybrids of cocaine preferring (C57BL/6J) and nonpreferring (ICR) mice.Methods ICR and C57BL/6J parental strains were compared to hybrids with 75% ICR:25% C57BL/6J, 50% ICR:50% C57BL/6J, and 25% ICR:75% C57BL/6J genetic backgrounds for acquisition of sucrose pellet and intravenous cocaine self-administration in 1-h test sessions. Mice that acquired cocaine self-administration were subsequently tested in a between-session self-administration dose-response procedure.Results Increasing presence of C57BL/6J genes increased the percentage of mice that acquired sucrose pellet self-administration in the first test session. In lever-trained mice, only 19% of ICR mice met acquisition criteria for cocaine self-administration after 15 sessions, whereas 76% of C57BL/6J mice met acquisition criteria, although both strains initially sampled a similar number of cocaine injections. Increasing the percentage of C57BL/6J genes in the nonpreferring ICR background to 50 and 75% led to increasing percentages of mice that met acquisition criteria to 31 and 52%, respectively. In mice that acquired self-administration, only mice with 75% C57BL/6J genes showed a typical inverted U-shaped self-administration dose–response curve, whereas the curve was flat across doses for mice with ≤50 and 100% C57BL/6J genes.Conclusions The findings are consistent with a genetically based dose-dependent enhancement of cocaine reinforcement by C57BL/6J genes. These results suggest that heritable traits impart a substantial genetic load that facilitates the propensity for cocaine addiction among individuals in outbred populations.     

Arginase enzymes in isolated airways from normal and nitric oxide synthase 2-knockout mice exposed to ovalbumin

Arginase has been suggested to compete with nitric oxide synthase (NOS) for their common substrate, l-arginine. To study the mechanisms underlying this interaction, we compared arginase expression in isolated airways and the consequences of inhibiting arginase activity in vivo with NO production, lung inflammation, and lung function in both C57BL/6 and NOS2 knockout mice undergoing ovalbumin-induced airway inflammation, a mouse model of asthma.Arginases I and II were measured by western blot in isolated airways from sensitized C57BL/6 mice exposed to ovalbumin aerosol. Physiological and biochemical responses - inflammation, lung compliance, airway hyperreactivity, exhaled NO concentration, arginine concentration - were compared with the responses of NOS2 knockout mice. NOS2 knockout mice had increased total cells in lung lavage, decreased lung compliance, and increased airway hyperreactivity. Both arginase I and arginase II were constitutively expressed in the airways of normal C57BL/6 mice. Arginase I was up-regulated approximately 8-fold in the airways of C57BL/6 mice exposed to ovalbumin. Expression of both arginase isoforms were significantly upregulated in NOS2 knockout mice exposed to ovalbumin, with about 40- and 4-fold increases in arginases I and II, respectively. Arginine concentration in isolated airways was not significantly different in any of the groups studied. Inhibition of arginase by systemic treatment of C57BL/6 mice with a competitive inhibitor, Nω-hydroxy-nor-l-arginine (nor-NOHA), significantly decreased the lung inflammatory response to ovalbumin in these animals.We conclude that NOS2 knockout mice are more sensitive to ovalbumin-induced airway inflammation and its sequelae than are C57BL/6 mice, as determined by increased total cells in lung lavage, decreased lung compliance, and increased airway hyperreactivity, and that these findings are strongly correlated with increased expression of both arginase isoforms in the airways of the NOS2 knockout mice exposed to ovalbumin.     

Distribution and excretion of 2,3,7,8-tetrachlorodibenzofuran in C57BL/6J and DBA/2J mice

The distribution and excretion of the toxic pollutant, 2,3,7,8-tetrachlorodibenzofuran (TCDF), was studied in male C57BL/6J and DBA/2J mice (22–29 g). [¹⁴C]TCDF was administered iv at a dose of 0.1 μmmol/kg. The liver was the major site of TCDF accumulation, with more TCDF in the livers of C57BL/6J mice compared to DBA/2J mice. TCDF had a half-life of approximately 1.8 days in the livers of both strains. At 7 hr and 1 day, respectively, radioactivity was redistributed to adipose tissue of C57BL/6J mice and DBA/2J mice. The terminal $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of TCDF in adipose tissue of C57BL/6J mice was 1.1 days, whereas it was 6.8 days in DBA/2J mice; the sixfold longer half-life in DBA/2J mice may be related to the approximately 36% greater adipose tissue content of this strain which may sequester more TCDF. More than 80 and 55% of the dose was excreted in the feces of C57BL/6J and DBA/2J mice, respectively, within 10 days as polar metabolites. The whole body half-life of TCDF was 2 days in C57BL/6J and 4 days in DBA/2J mice. Thus, DBA/2J mice sequester more of the TCDF dose in adipose tissue, accounting for a relatively slower rate of clearance and lower concentrations of TCDF at the putative target site(s) for toxic action.     

Correlation of inbred mouse sensitivity to nitrous oxide antinociception with brain nitric oxide synthase activity following exposure to nitrous oxide

Inhibition of nitric oxide synthase (NOS) antagonizes nitrous oxide (N2O)-induced antinociception in mice. This study was conducted to compare brain NOS activity in high responding C57BL/6 mice, low responding DBA/2 mice and S5 mice selectively bred for low responsiveness to N2O. Exposure to 70% N2O suppressed acetic acid-induced abdominal constrictions in C57BL/6 mice but not DBA/2 or S5 mice. N2O exposure also elevated NOS activity in brains of C57BL/6 mice but not DBA/2 or S5 mice. The absence of these effects in DBA/2 or S5 mice is further support for the hypothesis that nitric oxide (NO) may play a critical role in N2O-induced antinociception in mice.     

水合氯醛在C57BIM6小鼠麻醉中的应用研究

目的探索不同浓度的水合氯醛对C57BL／6小鼠的麻醉效果。方法将60只C57BL／6小鼠随机分为6组,A（2．5％、0．06mL／10g）、B（2．5％、0．1mL／10g）、C（5％、0．06mL／10g）、D（5％、0．1mL／10g）、E（10％、0．06mL/10g）、F（10％、0．1mL／10g）,分别进行腹腔注射水合氯醛麻醉实验,观察临床表现、诱导时间反维持时间。结果B、c、D和E组取得不同的麻醉效果,分别在3．34±0．48min、14．93±3．59rain、4．72±3．02min、9．20±1．51min进入麻醉状态,维持时间分别为45．74±1．94rain、44．18±8．64rain、179．25±3．99min、100．05±22．33rain。结论根据不同实验需要,选择水合氯醛恰当的浓度与剂量行腹腔注射麻醉,是安全有效的。     

Genetic resistance of mice to persistent infection with Mycobacterium lepraemurium in vitro: association with macrophage bactericidal responsiveness to lymphokines and dissociation from production of hydrogen peroxide by macrophages

Peritoneal and splenic adherent macrophages (SAC) from M. lepraemurium susceptible (C3H/HeJ) and resistant (C57B1/6J) mice were studied for their abilities to generate H2O2 in vitro. Unexpectedly, SAC from the susceptible C3H/HeJ strain produced more H2O2 than those of the resistant C57BL/6J. In vivo sensitization with M. bovis (BCG), or C. parvum increased production of H2O2 by SAC from both strains, whereas in vivo sensitization with M. lepraemurium enhanced H2O2 production only in the C3H/HeJ susceptible strains. In vitro addition of a crude lymphokine enhanced H2O2 production by C3H/HeJ SAC more than by C57BL/6J SAC. In vitro addition of M. lepraemurium caused an inhibition of H2O2 production by SAC from both strains but the inhibition was greater for the resistant C57BL/6J strain. M. lepraemurium phagocytosed in vitro by untreated peritoneal macrophages of both mouse strains were morphologically altered to the same extent. However, the addition of lymphokine dramatically increased the degree of bacterial lysis in only the C57BL/6J strain. These results, support the view that H2O2 plays a limited, if any, role in the protection of the host from M. lepraemurium and may even contribute to susceptibility by inhibiting the host's immune response.