Non-carcinogenicity of Capsaicinoids in B6C3F1 Mice

The carcinogenicity of a mixture of capsaicinoids (64.5% capsaicin and 32.6% dihydrocapsaicin) was examined in B6C3F₁ mice. In a 13-week toxicity study, renal toxicity was observed in 1% capsaicinoid-treated males. Next, groups of 50 mice of each sex were given 0, 0.025, 0.083 or 0.25% capsaicinoids in powdered diet for 79 weeks and killed in week 83. Food intake was reduced in mice of all capsaicinoid-treated groups, especially females, because of the pungency of capsaicinoids, and inhibition of body weight gain was apparent in females. The numbers of tumour-bearing females in the high-dose groups were significantly lower than that in the controls, and the incidences of hepatocellular neoplasms in both sexes were negatively correlated with the dose of capsaicinoids (Cochran–Armitage trend test). Renal cell adenomas developed in one mouse each of 0.025 and 0.25% capsaicinoid-treated males. The incidences of other tumours were similar in the treated and control groups. Thus, the present study indicated that a mixture of capsaicinoids is not carcinogenic in B6C3F₁ mice.     

Carcinogenicity study of 1,1-Bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane in B6C3F1 mice

1,1-Bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane (BBTC) is widely used in the manufacture of rubber. The present carcinogenicity study in B6C3F₁ mice was carried out in order to assess its potential to induce tumours. BBTC was administered at dietary levels of 0 (control), 0.25 and 0.5% for 78 wk; these dose levels were selected on the basis of a subchronic toxicity study, in which body weights were depressed to less than 90% of the control group values and swelling of hepatocytes was histologically evident in animals fed 1% BBTC or more in the diet. Neoplasms were found in all groups, including the control group, but there were no significant differences between groups of either sex in mortality, tumour incidences or tumour distribution. All tumours were considered to be spontaneous because of the similarity to background data for B6C3F₁ mice. This study thus provides no evidence of carcinogenicity of BBTC in B6C3F₁ mice.     

Long-term toxicity and carcinogenicity test of ammonia-process caramel colouring given to B6C3F1 mice in the drinking-water

Caramel colouring (ammonia process) was given at levels of 0 (control), 1.25 and 5.0% in the drinking-water to groups of 50 male and 50 female mice for 96 wk, and then all the animals were maintained without caramel for a further 8 wk. Males given 5.0% caramel showed increased cumulative mortality from wk 100 to the end of the experiment. The white blood cell count in treated males was significantly elevated in a dose-related manner. However, these changes were not considered to be biologically significant. There were no treatment-related effects on clinical signs, body or organ weights, results of urine analyses, or histological features. Therefore, this study did not demonstrate any carcinogenic effect of caramel on mice at levels of up to 5.0% in the drinking-water.     

Central effects of prostaglandins E2, A1 and F2α in adult fowls

Adult fowls (Gallus domesticus) with cannulae chronically implanted into the 3rd cerebral ventricle, the anterior or posterior hypothalamus and various other sites of the brain received infusions of prostaglandins (PG) E₂, A₁ or F_2α. The effects of these drugs on behaviour, posture, electrocortical activity and body temperature were studied.Prostaglandin E₂ and PGA₁ infused into the 3rd cerebral ventricle and into the hypothalamus induced sedation and/or sleep and increased body temperature. Prostaglandin F_2α lowered body temperature but did not affect behaviour.Behavioural, electrocortical and body temperature changes were dose-dependent. Prostaglandin E₂ was more potent than FGA₁Infusion of PGE₂, PGA₁ and PGF_2α into other cerebral areas e.g. paleostriatum augmentatum, telencephalon and mesencephalon lacked effects on behaviour, electrocortical activity and body temperature.The site through which behavioural, electrocortical and body temperature effects of prostaglandins E₂ and A₁ were mediated appears to be the hypothalamus.     

Absence of carcinogenic response in F344 rats and B6C3F1 mice given D-mannitol in the diet for two years

Diets containing 2.5 or 5% d-mannitol were fed to groups of 50 F344 rats and 50 B6C3F₁ mice of each sex for 103 wk. Similar groups served as controls. There were no significant differences in survival between treated and control rats or between treated and control mice. Mean body weights were similar in treated and control male rats and in treated and control female mice. Throughout the study, the mean body weights of female rats on the 5% diet were slightly (< 10%) lower than those of the controls, and by the end of the study the mean body weights of treated male mice were slightly (c. 10%) higher than those of the controls. Feed consumption by treated and control animals was approximately the same in rats and mice of either sex. The incidence of dilation of the gastric fundal gland was higher (46%) in treated female rats than in the controls (12%). A mild nephrosis, characterized by focal vacuolization of the renal tubular epithelium, showed an increased incidence in treated mice of both sexes and was considered to be related to the administration of d-mannitol. There were no statistically significant increases in tumour incidence in any of the treated groups when compared with the corresponding controls. Under the conditions of this bioassay, d-mannitol was not shown to be carcinogenic for F344 rats or B6C3F₁ mice of either sex.     

Carcinogenicity and toxicity study of m-phenylenediamine administered in the drinking-water to (C57BL/6 × C3H/He)F1 mice

m-Phenylenediamine (m-PDA, CAS: 108-45-2), a component of hair-dye formulations, was administered in the drinking-water to groups of female and male (C57BL/6 x C3H/He)F1 (B6C3F1) mice at concentrations of 0.02 or 0.04% for 78 wk. All the surviving mice were killed after a further 5-7 wk on untreated drinking-water, 83-85 wk after the start of treatment. Survival of the treated mice was similar to that of the corresponding controls. Body weights were significantly lower in high-dose females and males and somewhat lower in low-dose females than in the controls. The incidences of hepatocellular tumours were low to moderate in all male groups and in the control females, but the treated groups had significantly lower incidences than the controls. A few tumours of the lungs, haematopoietic organs and other organs and tissues were observed in all female and male groups. However, there were no statistically significant increases in the incidences of tumours in these organs and tissues in m-PDA-treated mice of either sex. Under the conditions of this study m-PDA showed no carcinogenic potential in either female or male B6C3F1 mice when administered in drinking-water. No non-neoplastic changes attributable to the compound were found in the treated mice, except for the deposition of brown pigment in follicular epithelial cells of the thyroid gland and in macrophages in some organs and tissues, and pigment impregnation of the bronchioli.     

14-day and 90-day toxicity studies of C.I. Pigment Red 3 in Fischer 344 rats and B6C3F1 mice

Treatment of F344 rats and B6C3F₁ mice with C.I. Pigment Red 3 in the diet (10, 5.0, 2.5, 1.25, 0.6 or 0.3%) for 14 and 90 days resulted in haematological alterations consistent with haemolytic anaemia. Rats appeared to be more sensitive than mice to the haematological effects. Histological lesions were observed in rats and mice after exposure for 90 days. Target organs in the rat were the spleen, bone marrow, liver and kidney. Lesions in the spleen consisted of a haematopoietic cell proliferation, iron-positive pigment and congestion of the red pulp, and inflammation of the splenic capsule. Changes in the livers of rats consisted of haematopoietic cell proliferation and iron-positive pigment in Kupffer cells. Haematopoietic cell proliferation also occurred in the bone marrow of treated rats. The presence of iron-positive pigment and a slightly increased incidence of protein casts were seen in the kidney. Target organs in mice were the spleen, liver and kidney. Histological lesions in mice after exposure for 90 days included increased haematopoietic cell proliferation in the liver and spleen, and iron-positive pigment in the spleen. Mild cytomegaly of the renal tubular epithelia was also observed in exposed mice.     

Induction of oxidative stress response by the mycotoxin patulin in mammalian cells.

Patulin (PAT), a mycotoxin mainly produced by Penicillium and Aspergillus, is found in various foods and feeds. In the present study, its effects on oxidative stress in various mammalian cell lines were investigated. When cell-permeating fluorescent dyes were used as indicators of the generation of reactive oxygen species (ROS), we found that PAT treatment directly increased intracellular oxidative stress in human embryonic kidney (HEK293) and human promyelocytic leukemia (HL-60) cells. Lipid peroxidation levels were also significantly increased in HL-60 cells and mouse kidney homogenates treated with PAT. Suppression of CuZn-superoxide dismutase (SOD) expression in mammalian cells by small interfering RNA resulted in an increase in PAT-mediated membrane damage, while overexpression of human CuZn-SOD or catalase led to a reduction in damage, indicating the involvement of ROS in PAT toxicity. Pretreatment of HEK293 cells with Tiron, a free radical scavenger, reduced the phosphorylation levels of extracellular signal-regulated kinase (ERK) 1/2 elicited by PAT. The ERK1/2 signaling pathway inhibitor, U0126, also significantly decreased the levels of ROS associated with PAT treatment. These findings indicate that PAT treatment results in the ROS production in mammalian cells, and ROS partially contributes to PAT-induced cytotoxicity. Activation of ERK1/2 signaling pathway is correlated with PAT-mediated ROS.     

Isoform specificity of cardiac glycosides binding to human Na,K-ATPase α1β1, α2β1 and α3β1

Cardiac glycosides inhibit the Na⁺,K⁺-ATPase and are used for the treatment of symptomatic heart failure and atrial fibrillation. In human heart three isoforms of Na⁺,K⁺-ATPase are expressed: α₁β₁, α₂β₁ and α₃β₁. It is unknown, if clinically used cardiac glycosides differ in isoform specific affinities, and if the isoforms have specific subcellular localization in human cardiac myocytes. Human Na⁺,K⁺-ATPase isoforms α₁β₁, α₂β₁ and α₃β₁ were expressed in yeast which has no endogenous Na⁺,K⁺-ATPase. Isoform specific affinities of digoxin, digitoxin, β-acetyldigoxin, methyldigoxin and ouabain were assessed in [³H]-ouabain binding assays in the absence or presence of K⁺ (each n = 5). The subcellular localizations of the Na⁺,K⁺-ATPase isoforms were investigated in isolated human atrial cardiomyocytes by immunohistochemistry. In the absence of K⁺, methyldigoxin (α₁ > α₃ > α₂) and ouabain (α₁ = α₃ > α₂) showed distinct isoform specific affinities, while for digoxin, digitoxin and β-acetyldigoxin no differences were found. In the presence of K⁺, also digoxin (α₂ = α₃ > α₁) and β-acetyldigoxin (α₁ > α₃) had isoform specificities. A comparison between the cardiac glycosides demonstrated highly different affinity profiles for the isoforms. Immunohistochemistry showed that all three isoforms are located in the plasma membrane and in intracellular membranes, but only α₁β₁ and α₂β₁ are located in the T-tubuli. Cardiac glycosides show distinct isoform specific affinities and different affinity profiles to Na⁺,K⁺-ATPase isoforms which have different subcellular localizations in human cardiomyocytes. Thus, in contrast to current notion, different cardiac glycoside agents may significantly differ in their pharmacological profile which could be of hitherto unknown clinical relevance.     

Role of glutathione conjugation in the hepatotoxicity and immunotoxicity induced by 1-bromopropane in female BALB/c mice

1-Bromopropane (1-BP) is used as a cleaning agent or adhesive solvent in the workplace. In the present study, the hepatotoxic and immunotoxic effects of 1-bromopropane and its conjugation with glutathione (GSH) were investigated in female BALB/c mice. The animals were treated orally with 200, 500 and 1000 mg kg(-1) of 1-BP in corn oil for a dose response study or treated orally with 1000 mg kg(-1) of 1-BP for 6, 12, 24 and 48 h for a time course study. The hepatic and splenic contents of GSH were significantly decreased by 1-BP in a dose-dependent manner. S-propyl GSH was identified in livers following treatment with 1-BP by liquid chromatography-electrospray ionization tandem mass spectrometry. When the production of conjugates from 1-BP was investigated in livers following oral treatment with 1000 mg kg(-1) of 1-BP for 6, 12, 24 and 48 h, the GSH conjugates were detected maximally 6 h after treatment. Treatment of mice with 1-BP increased the serum activity of alanine aminotransferase dose-dependently. The oral 1-BP treatment significantly suppressed the antibody response to a T-dependent antigen and the production of splenic intracellular IL-2 in response to Con A in a dose-dependent manner. The present results suggested that 1-BP could cause hepatotoxicity and immunotoxicity as well as depletion of GSH content due to the formation of GSH conjugates.     

Gestational Exposure to Perfluorooctane Sulfonate Suppresses Immune Function in B6C3F1 Mice

Perfluorinated alkyl acids (PFAAs) are used in a multitude ofapplications and are categorized as high-production volume chemicalsproduced in quantities exceeding 10,000 lbs/year. As a result,widespread exposure has been documented in adults, children,and infants. It is generally accepted that children are moresensitive to the effects of xenobiotic exposures during fetaland postnatal periods of development; therefore, considerableefforts are required to investigate the potential impact ofa model PFAA, perfluorooctane sulfonate (PFOS) on children'simmunological health. Using the pairing of female C57BL/6N micewith male C3H/HeJ, developmental immunotoxicity was evaluatedin B6C3F1 pups following oral maternal exposure to PFOS on gestationsdays 1–17. Exposure levels included 0.1, 1, and 5 mg/kg/dayPFOS. Natural killer (NK) cell activity, SRBC IgM plaque assay,CD4/8 lymphocytic subpopulations, nitrite production in peritonealmacrophages, and body/organ weights were evaluated at 4 and8 weeks of age in F1 pups. No significant dose-responsive changesin maternal or pup body weights, flow cytometry, or macrophagefunction were observed, yet hepatomegaly was indicated in F1male pups at 4 weeks of age. Functional deficits were not evidentuntil 8 weeks of age when NK cell function and IgM productionwere significantly decreased. When compared with females, malepups were more sensitive to the effects of PFOS thereby establishinga no observed adverse effect level and low observed adverseeffect level of 0.1 and 1.0 mg/kg/day (males only) followingmaternal PFOS exposure level, respectively. This study establishesthat the developing immune system is sensitive to the effectsof PFOS and results in functional deficits in innate and humoralimmunity detectable at adulthood.     

A threonine residue in the M2 region of the β1 subunit is needed for expression of functional α1β1 GABAA receptors

Although there is a high degree of homology in the M2 transmembrane segments of α₁ and β₁ subunits, subunit-specific effects were observed in α₁β₁ GABA_A receptors expressed in Spodoptera frugipedra (Sf9) cells when the conserved 13′ threonine residue in the M2 transmembrane region was mutated to alanine. When threonine 263 (13′) was mutated to alanine in the β₁ subunit, high-affinity muscimol binding and the response to GABA were abolished. This did not occur when the threonine 263 (13′) was mutated to alanine in the α₁ subunit, but the rate of desensitisation increased and the effect of bicuculline, a competitive inhibitor, was reduced. The results show differential effects of subunits on receptor function and support a role for M2 in desensitisation.     

Glycidol modulation of the immune responses in female B6C3F1 mice

The immunotoxic potential of glycidol was evaluated in female B6C3F1 mice using a battery of functional assays and three host resistance models. Glycidol was administered to the animals by oral gavage as a solution in sterile distilled water daily for 14 days at doses of 25, 125 and 250 mg/kg. In tier I, we observed that glycidol exposure produced a dose-related decrease in splenocyte IgM antibody-forming cell response to sheep red blood cells (sRBC); the spleen natural killer (NK) cell activity was also decreased. A decrease in B cell proliferative responses to anti-IgM F(ab')2 and/or interleukin-4 (IL-4) was observed while the splenocyte proliferative responses to T cell mitogen ConA and B cell mitogen LPS were not affected. The splenocyte proliferative response to allogeneic cells as evaluated in the mixed leukocyte reaction (MLR) to DBA/2 spleen cells was not affected. In tier II, we found that exposure to glycidol decreased the number and percentage of B cells and the absolute number of CD4+ T cells in the spleen while the number of total T cells, CD8+ T cells and CD4+CD8+ T cells was not affected. The cytotoxic T lymphocyte (CTL) response to mitomycin C-treated P815 mastocytoma was not affected; the cytotoxic activity of peritoneal macrophages was not suppressed. Moreover, the host resistance to Listeria monocytogenes was not affected although a slight increase in host resistance to Streptococcus pneumoniae was observed. However, exposure to glycidol decreased host resistance to the B16F10 melanoma tumor model with the maximal tumor formation in lung observed in the high dose group. Overall, these dada support the finding that glycidol is an immunosuppressive agent in female B6C3F1 mice.     

Effect of dimethylnitrosamine on the induction of chromosomal aberrations in male mice and their F1 offspring

C₃H strain male mice were treated with dimethylnitrosamine (DMN) during 8 successive weeks at dose levels of 0.05 and 0.1 mg/kg per day: chromosomal translocations were not produced.     

Immunomodulatory activity of orphan drug Elmiron® in female B6C3F1/N mice

Interstitial cystitis (IC) is a chronic disorder characterized by bladder discomfort and urinary urgency in the absence of identifiable infection. Despite the expanding use in IC treatment and other chronic conditions, the effects of Elmiron® treatment on immune system remain unknown. Therefore, female B6C3F1/N mice were orally administered Elmiron® daily for 28-days at doses of 63, 125, 250, 500 or 1000 mg/kg to evaluate its immunomodulatory effects. Mice treated with Elmiron® had a significant increase in absolute numbers of splenic macrophages (63, 500 and 1000 mg/kg) and natural killer (NK) cells (250 and 1000 mg/kg). Elmiron® treatment did not affect the humoral immune response or T cell proliferative response. However, innate immune responses such as phagocytosis by liver macrophages (1000 mg/kg) and NK cell activity were enhanced (500 and 1000 mg/kg). Further analysis using a disease resistance model showed that Elmiron®-treated mice demonstrated significantly increased anti-tumor activity against B16F10 melanoma cells at the 500 and 1000 mg/kg doses. Collectively, we conclude that Elmiron® administration stimulates the immune system, increasing numbers of specific cell populations and enhancing macrophage phagocytosis and NK cell activity in female B6C3F1/N mice. This augmentation may have largely contributed to the reduced number of B16F10 melanoma tumors.     

HPLC法测定谷维素双维B片中维生素B1和维生素B6的含量

目的:建立HPLC同时测定谷维素双维B片中维生素B1和维生素B6的含量.方法:采用C18柱;以0.04%戊烷磺酸钠-2%冰醋酸.甲醇(35:45:20)为流动相;检测波长:276nm;流速:1.0 mL·min-1.结果:维生素B1在50.64～118.16μg·L-1范围内峰面积与浓度具有良好线性关系,维生素B6在117.84～274.96μg·L-1范围内峰面积与浓度具有良好线性关系;维生素B1的回收率为:99.41%,RSD 1.45%(n=6);维生素B6的回收率为:99.16%,RSD 1.42%(n=6).结论:该方法准确、灵敏度高、重现性好、结果准确.     

Potentiated β-cell response to non-glucose stimuli in insulin-resistant C57BL/6J mice

Insulin secretion in response to acetylcholine receptor activation by carbachol in insulin resistance induced by 12 weeks of high-fat diet in C57BL/6J mice is exaggerated. To study whether this persists after a longer period of time and also involves other non-glucose stimuli, we fed C57BL/6J mice a high-fat diet for 24 weeks. Both hyperinsulinemia (341±33 vs. 148±15 pmol/l) and slight hyperglycemia (7.8±0.2 vs. 6.1±0.1 mmol/l) were evident at this time point. The insulinotropic response to high dose carbachol (0.53 μmol/kg; 3403±377 vs. 1595±429 pmol/l), to the glucose analogue, 2-deoxyglucose (6 mmol/kg; 2014±315 vs. 1167±200 pmol/l), to cholecystokinin-8 (15.9 nmol/kg; 499±93 vs. 119±40 pmol/l) and to glucagon-like peptide-1 (32 nmol/kg; 307±86 vs. 71±9 pmol/l), were all exaggerated in mice given high-fat diet. In contrast, the insulin response to glucose was impaired. This shows that insulin resistance is accompanied by a general islet supersensitivity to non-glucose stimuli, which persists over a long period of time.     

Cis‐bifenthrin induces immunotoxicity in adolescent male C57BL/6 mice

Bifenthrin (BF) is an important synthetic pyrethroid. Previous studies have demonstrated that cis‐BF exhibits toxic effects on development, the neurological, reproductive and endocrine system. In this study, we evaluated the immunotoxicity caused by cis‐BF in adolescent male C57BL/6 mice. Mice were exposed orally to 0, 5, 10, and 20 mg/kg/d for 3 weeks. The results showed that body weight, spleen weight, and splenic cellularity decreased in mice exposed to 20 mg/kg/d cis‐BF. Additionally, we found that the mRNA levels of the pro‐inflammatory factors IL‐1β, IL‐6, CXCL‐1, and TNF‐α, in peritoneal macrophages, the spleen, and the thymus were inhibited in the cis‐BF‐treated groups. Moreover, MTT assays demonstrated that cis‐BF inhibited splenocyte proliferation stimulated by LPS or Con A, as well as the secretion of IFN‐γ on Con A stimulation. Collectively, the results of this study suggest that exposure to cis‐BF has the potential to induce immunotoxicity in adolescent male C57BL/6 mice.