著者

Sugiyama Hideo Terada Hiroshi Isomura Kimio IIJIMA Ikuyo KOBAYASHI Jun KITAMURA Kiyoshi

出版者

日本毒性学会

雑誌

Journal of toxicological sciences (ISSN:03881350)

巻号頁・発行日

vol.34, no.4, pp.417-425, 2009-08-01

参考文献数

24

被引用文献数

2 15

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The isotope ²¹⁰Po was suspected of being involved in the death of a former Russian intelligence agent in 2006 in the UK. Although human exposure to this natural radionuclide in foods is estimated to be high, few studies are available. UNSCEAR Report 2000 does not contain data on ²¹⁰Po concentrations of foodstuffs in Japan. We analyzed samples of the everyday Japanese diet cooked with foodstuffs purchased at supermarkets in 7 major domestic cities in 2007-2008. ²¹⁰Po was quantified by alpha spectrometry and natural radionuclides such as ⁴⁰K by gamma spectrometry. The daily intake and committed effective dose of ²¹⁰Po, ⁴⁰K, and other natural radionuclides for Japanese adults were calculated. Daily intake was 0.34-1.84 (mean ± σ : 0.66 ± 0.53) and 68.5-94.2 (81.5 ± 8.5) Bq/d and the committed effective dose was 0.15-0.81 (0.29 ± 0.24) and 0.16-0.21 (0.18 ± 0.02) mSv for ²¹⁰Po and ⁴⁰K, respectively, comprising a high percentage of the total exposure. The total of the mean committed effective dose for the two nuclides (0.47 mSv) was higher than the annual effective dose from ingestion of foods reported by UNSCEAR 2000 (0.29 mSv). The mean committed effective dose of ⁴⁰K in the 7 major Japanese cities was comparable to the global average (0.17 mSv). The dietary exposure of Japanese adults can be characterized by a higher ²¹⁰Po contribution than in other countries. Of the total daily dietary ²¹⁰Po exposure (13 food categories excluding water) for adults in Yokohama, about 70% was from fish/shellfish and 20% from vegetables/mushrooms/seaweeds, reflecting preferences of Japanese to eat a considerable amount of fish/shellfish containing high ²¹⁰Po concentrations.

著者

Akemi SAITO Masaharu YAMAMOTO

出版者

The Japanese Society of Toxicology

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.21, no.3, pp.195-200, 1996-08-25 (Released:2008-02-21)

参考文献数

18

被引用文献数

40 54

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The oral toxicity of capsaicin was investigated in mice and rats. Oral LD50 values were 118.8 mg/kg for male and 97.4 mg/kg for female mice, and 161.2 mg/kg for male and 148.1 mg/kg for female rats. Major toxic symptoms in mice were salivation, erythema of skin, staggering gait, bradypnea and cyanosis. Some animals showed tremor, clonic convulsion, dyspnea and lateral or prone position and then died 4 to 26 min after dosing. Survivors recovered within 6 hr in mice and 24 hr in rats. Toxic symptoms of fats were almost the same as mice, but rats showing higher incidence of cyanosis, clonic or tonic convulsion, dyspnea and lateral position, and the recovery was later than mice. The cause of death by capsaicin may be due to hypotension and respiratory paralysis in both animals, although the pathophysiology of death is not clearly understood. At pathological examination, erosion and ulcer of gastric fundus were seen in dead animals, while no pathological change was seen in surviving ones.

著者

Harumi Okuyama Naoki Ohara Kenjiro Tatematsu Shinya Fuma Tomoyuki Nonogaki Kazuyo Yamada Yuko Ichikawa Daisuke Miyazawa Yuko Yasui Seijiro Honma

出版者

The Japanese Society of Toxicology

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.35, no.5, pp.743-747, 2010-10-01 (Released:2010-10-01)

参考文献数

25

被引用文献数

7 13 5

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Canola and some other types of oil unusually shorten the survival of stroke-prone spontaneously hypertensive rats (SHRSP), compared with soybean oil, perilla oil and animal fats. Since differential effects of canola and soybean oil on steroid hormone metabolism were suggested by a preliminary DNA microarray analysis as a reason for this, the steroid hormone levels in the serum and tissues of SHRSP fed different oils were investigated. The testosterone levels in the serum and the testes were found to be significantly lower in the canola oil group than in the soybean oil group, while no significant differences were detected in the corticosterone and estradiol levels in tissues. In a second experiment, it was found that hydrogenated soybean oil, with a survival-shortening activity comparable to that of canola oil, also decreased the testosterone level in testes to a similar degree. The testosterone-lowering activity of canola and hydrogenated soybean oil observed in SHRSP was considered in relation to other factors possibly affecting the physiology of SHRSP.

著者

Sanghwa Kim Seong-Ho Hong Choon-Keun Bong Myung-Haing Cho

出版者

The Japanese Society of Toxicology

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.40, no.5, pp.535-550, 2015-10-01 (Released:2015-09-10)

参考文献数

100

被引用文献数

31 49

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Air freshener could be one of the multiple sources that release volatile organic compounds (VOCs) into the indoor environment. The use of these products may be associated with an increase in the measured level of terpene, such as xylene and other volatile air freshener components, including aldehydes, and esters. Air freshener is usually used indoors, and thus some compounds emitted from air freshener may have potentially harmful health impacts, including sensory irritation, respiratory symptoms, and dysfunction of the lungs. The constituents of air fresheners can react with ozone to produce secondary pollutants such as formaldehyde, secondary organic aerosol (SOA), oxidative product, and ultrafine particles. These pollutants then adversely affect human health, in many ways such as damage to the central nervous system, alteration of hormone levels, etc. In particular, the ultrafine particles may induce severe adverse effects on diverse organs, including the pulmonary and cardiovascular systems. Although the indoor use of air freshener is increasing, deleterious effects do not manifest for many years, making it difficult to identify air freshener-associated symptoms. In addition, risk assessment recognizes the association between air fresheners and adverse health effects, but the distinct causal relationship remains unclear. In this review, the emitted components of air freshener, including benzene, phthalate, and limonene, were described. Moreover, we focused on the health effects of these chemicals and secondary pollutants formed by the reaction with ozone. In conclusion, scientific guidelines on emission and exposure as well as risk characterization of air freshener need to be established.

著者

Jeffrey C. Raber Sytze Elzinga Charles Kaplan

出版者

日本毒性学会

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.40, no.6, pp.797-803, 2015-12-01 (Released:2015-11-10)

参考文献数

9

被引用文献数

6 141

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Cannabis concentrates are gaining rapid popularity in the California medical cannabis market. These extracts are increasingly being consumed via a new inhalation method called ‘dabbing’. The act of consuming one dose is colloquially referred to as “doing a dab”. This paper investigates cannabinoid transfer efficiency, chemical composition and contamination of concentrated cannabis extracts used for dabbing. The studied concentrates represent material available in the California medical cannabis market. Fifty seven (57) concentrate samples were screened for cannabinoid content and the presence of residual solvents or pesticides. Considerable residual solvent and pesticide contamination were found in these concentrates. Over 80% of the concentrate samples were contaminated in some form. THC max concentrations ranged from 23.7% to 75.9% with the exception of one outlier containing 2.7% THC and 47.7% CBD. Up to 40% of the theoretically available THC could be captured in the vapor stream of a dab during inhalation experiments. Dabbing offers immediate physiological relief to patients in need but may also be more prone to abuse by recreational users seeking a more rapid and intense physiological effect.

著者

Toshi WATANABE Yoshihiro KISHIKAWA Wataru SHIRAI

出版者

The Japanese Society of Toxicology

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.22, no.2, pp.141-152, 1997-05-25 (Released:2008-02-21)

参考文献数

17

被引用文献数

11 12

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Alkaline ionized water (AKW) produced by the electrolysis of tap water (TPW) was given to pregnant rats throughout gestation. AKW was subsequently given to infants as a test group until 15 weeks old to determine changes in body and organ weights, erythrocyte hexokinase (HK) activity and histological preparations of myocardiac muscle. The results were compared with those for rats given TPW. Body weight of male and female rats given AKW at 3 to 11 weeks of age after birth significantly increased beyond control group values. Organ weights of offspring at 15weeks-old showed no statistical difference for either group. HK activity, the rate-determining enzyme in erythrocyte glycolysis, significantly increased in males given AKW at 15 weeks-old. This suggests that AKW intake causes elevation of metabolic activity. Hyperkalemia was observed in males and females given AKW at 15 weeks-old. Especially in males, pathological changes of necrosis in myocardiac muscle were observed.

著者

Kosuke Kawamoto Itaru Sato Midori Yoshida Shuji Tsuda

出版者

日本毒性学会

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.35, no.6, pp.929-933, 2010-12-01 (Released:2010-12-01)

参考文献数

16

被引用文献数

1

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Several appliance manufacturers have recently released new type air purifiers that can disinfect bacteria, fungi and viruses by diffusing reactive oxygen species (ROS) into the air. In this study, mice were exposed to the outlet air from each of 3 air purifiers from different manufacturers (A, B, C), and the lung was examined for DNA damage, lipid peroxidation and histopathology to confirm the safety of these air purifiers. Neither abnormal behavior during exposure nor gross abnormality at necropsy was observed. No histopathological changes were also observed in the lung. However, significant increase of DNA damage was detected by the comet assay in the lung immediately after the direct exposure for 48 hr to models A and B, and for 16 hr to model B. As for model B, DNA migration was also increased by 2 hr exposure in a 1 m3 plastic chamber but not by 48 hr exposure in a room (12.6 m3). Model C did not cause DNA damage. Lipid peroxidation and 8-hydroxy deoxyguanosine (8-OH-dG) was not increased under the conditions DNA damage was detected by the comet assay. The present results revealed that some models of air purifiers that diffuse ROS potentially cause DNA damage in the lung although the mechanism was left unsolved.

著者

Shohei Kanie Mitsuhiro Fujieda Tomoaki Hitotsumachi Satoshi Suzuki Fumio Morita Kazuo Hakoi Hirofumi Yasui

出版者

The Japanese Society of Toxicology

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.42, no.3, pp.291-300, 2017-06-01 (Released:2017-05-11)

参考文献数

28

被引用文献数

3 3

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S-1 is an anticancer agent that consists of tegafur, gimeracil, and oteracil potassium at a molar ratio of 1:0.4:1. S-1 is used to treat metastatic and resectable gastric cancer. However, the extensive use of S-1 in clinical practice results in watery eyes, a serious clinical problem, which worsens patients’ quality of life. Although repeated instillation of artificial tears is recommended, therapy or prophylaxis against S-1-induced ocular toxicity has not been established. In the present study, we evaluated the alleviating effects of repeated artificial tear instillation on S-1-induced ocular toxicity in dogs. Ten beagle dogs (5 males and 5 females) were orally administered 3 mg/kg/day of S-1 for up to 21 days. Five drops of artificial tears were instilled to the left eye, eight times daily, within 6 hr after S-1 administration. The mean cornea staining score tended to be low in the left eye with repeated artificial tear instillation. In 4 out of 10 dogs, the corneal staining score of the left eye was more than 2-fold lower than that of the right eye. The incidence of dogs indicating normal tear drainage increased and stenosed tear drainage decreased by repeated artificial tear instillation. In conclusion, we demonstrated that artificial tear instillation can alleviate corneal surface damage induced by S-1 in dogs.

著者

Masahiko Yamaguchi Daisuke Araki Takeshi Kanamori Yasuko Okiyama Hirokazu Seto Masaki Uda Masahito Usami Yutaka Yamamoto Takuji Masunaga Hitoshi Sasa

出版者

日本毒性学会

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.42, no.6, pp.797-814, 2017-12-01 (Released:2017-11-16)

参考文献数

15

被引用文献数

9

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Safety assessments of cosmetics are carried out by identifying possible harmful effects of substances in cosmetic products and assessing the exposure to products containing these substances. The present study provided data on the amounts of cosmetic products consumed in Japan to enhance and complement the existing data from Europe and the United States, i.e., the West. The outcomes of this study increase the accuracy of exposure assessments and enable more sophisticated risk assessment as a part of the safety assessment of cosmetic products. Actual amounts of products applied were calculated by determining the difference in the weight of products before and after use by approximately 300 subjects. The results of the study of skincare products revealed that in comparison with the West, large amounts of lotions and emulsions were applied, whereas lower amounts of cream and essence were applied in Japan. In the study of sunscreen products, actual measured values during outdoor leisure use were obtained, and these were lower than the values from the West. The study of the use of facial mask packs yielded data on typical Japanese sheet-type impregnated masks and revealed that high amounts were applied. Furthermore, data were obtained on cleansing foams, makeup removers and makeup products. The data from the present study enhance and complement existing information and will facilitate more sophisticated risk assessments. The present results should be extremely useful in safety assessments of newly developed cosmetic products and to regulatory authorities in Japan and around the world.

著者

Akifumi Eguchi Hidenobu Miyaso Chisato Mori

出版者

日本毒性学会

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.41, no.5, pp.667-675, 2016-10-01 (Released:2016-09-24)

参考文献数

52

被引用文献数

9

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The toxicity of decabromodiphenyl ether (BDE-209) has been reported in several studies. However, there is not much known about the toxicological biomarkers that characterize BDE-209 exposure. In this study, we subcutaneously exposed mice to 0.025 mg/kg/day BDE-209 on postnatal days 1‑5 and sacrificed the animals at 12 weeks of age (day 84). Flow injection analysis and hydrophilic interaction chromatography-triple quadrupole mass spectrometry were used to determine the serum metabolomes of these mice in order to characterize the effects of BDE-209 exposure. Data analysis showed a good separation between control and exposed mice (R2 = 0.953, Q2 = 0.728, and ANOVA of the cross‑validated residuals (CV‑ANOVA): P‑value = 0.0317) and 54 metabolites were identified as altered in the exposed animals. These were selected using variable importance (VIP) and loadings scaled by a correlation coefficient criteria and orthogonal partial least squares discriminant analysis (OPLS‑DA). BDE‑209‑exposed mice showed lower levels of long-chain acylcarnitines and citrate cycle-related metabolites, and higher levels of some amino acids, long-chain phospholipids, and short-chain acylcarnitines. The disruption of fatty acid, carbohydrate, and amino acid metabolism observed in the serum metabolome might be related to the previously observed impaired spermatogenesis in mice with early postnatal exposure to a low dose of BDE-209.

著者

Nobuyuki Suzuki Ryuichi Kambayashi Ai Goto Hiroko Izumi-Nakaseko Yoshinori Takei Atsuhiko T Naito Atsushi Sugiyama

出版者

The Japanese Society of Toxicology

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.48, no.12, pp.645-654, 2023 (Released:2023-12-01)

参考文献数

27

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Antiparasitic ivermectin has been reported to induce cardiovascular adverse events, including orthostatic hypotension, tachycardia and cardiopulmonary arrest, of which the underlying pathophysiology remains unknown. Since its drug repurposing as an antiviral agent is underway at higher doses than those for antiparasitic, we evaluated the cardiovascular safety pharmacology of ivermectin using isoflurane-anesthetized beagle dogs (n=4). Ivermectin in doses of 0.1 followed by 1 mg/kg was intravenously infused over 10 min with an interval of 20 min, attaining peak plasma concentrations of 0.94 ± 0.04 and 8.82 ± 1.25 μg/mL, which were 29-31 and 276-288 times higher than those observed after its antiparasitic oral dose of 12 mg/body, respectively. The latter peak concentration was > 2 times greater than those inhibiting proliferation of dengue virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and hepatitis B virus in vitro. Ivermectin decreased heart rate without altering mean blood pressure, suggesting that ivermectin does not cause hypotension or tachycardia directly. Ivermectin hardly altered atrioventricular nodal or intraventricular conduction, indicating a lack of inhibitory action on Ca2+ or Na+ channel in vivo. Ivermectin prolonged QT interval/QTcV in a dose-related manner and tended to slow the repolarization speed in a reverse frequency-dependent manner, supporting previously described its IKr inhibition, which would explain Tpeak-Tend prolongation and heart-rate reduction in this study. Meanwhile, ivermectin did not significantly prolong J-Tpeakc or terminal repolarization period, indicating torsadogenic potential of ivermectin leading to the onset of cardiopulmonary arrest would be small. Thus, ivermectin has a broad range of cardiovascular safety profiles, which will help facilitate its drug repurposing.

著者

関田 清司 井上 達

出版者

一般社団法人 日本毒性学会

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.24, no.5, pp.App147-App158, 1999-12-20 (Released:2008-02-21)

参考文献数

69

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今日,コカインや覚せい剤などの薬物乱用問題は世界的な取り組の対象となっている。わが国においても,一時,減少傾向にあった覚せい剤の乱用者数が,特にこの数年,増加傾向と低年齢化を示しており危機に直面している。こうした,乱用される薬物は,生体に摂取されることにより,その薬理作用による高揚感や多幸感などの精神的「満足感」を引き起こす。脱し難い薬物依存の形成機序はともかくとして,薬物乱用はこの自覚効果の再体験への欲求にもとづく行動と考えられている。ところで近年,コカインや覚せい剤などのように麻薬及び向精神薬取締法などの法規の取締対象物として所持や使用が厳しく規制を受ける「違法な薬物」とは別に,これらの法的規制外で、多幸感や気分の高揚が得られるなどとの標傍のもとに,いわゆる「合法ドラッグ」と称する「商品」が流通している実態がある。現在取締対象となっている「乱用薬物」も、多くは今日の「合法ドラッグ」に似た位置づけにあったものと考えられるので、本稿では,代表的な「乱用薬物」であるコカインや覚せい剤などが乱用される機構を整理し,それらが法規制の対象になるに至った経緯などについて通覧することにより,今日の「合法ドラッグ」の性質やその危険性を明らかにすることを目的としている。

著者

Masayo Hirao-Suzuki Shuso Takeda Takayuki Koga Masufumi Takiguchi Akihisa Toda

出版者

The Japanese Society of Toxicology

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.45, no.4, pp.227-236, 2020 (Released:2020-04-01)

参考文献数

38

被引用文献数

1 15

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A growing body of experimental evidence strongly suggests that cannabidiolic acid (CBDA), a major component of the fiber-type cannabis plant, exerts a variety of biological activities. We have reported that CBDA can abrogate cyclooxygenase-2 (COX-2) expression and its enzymatic activity. It is established that aberrant expression of COX-2 correlates with the degree of malignancy in breast cancer. Although the reduction of COX-2 expression by CBDA offers an attractive medicinal application, the molecular mechanisms underlying these effects have not fully been established. It has been reported that COX-2 expression is positively controlled by peroxisome proliferator-activated receptor β/δ (PPARβ/δ) in some cancerous cells, although there is “no” modulatory element for PPARβ/δ on the COX-2 promoter. No previous studies have examined whether an interaction between PPARβ/δ-mediated signaling and COX-2 expression exists in MDA-MB-231 cells. We confirmed, for the first time, that COX-2 expression is positively modulated by PPARβ/δ-mediated signaling in MDA-MB-231 cells. CBDA inhibits PPARβ/δ-mediated transcriptional activation stimulated by the PPARβ/δ-specific agonist, GW501516. Furthermore, the disappearance of cellular actin stress fibers, a hallmark of PPARβ/δ and COX-2 pathway activation, as evoked by the GW501516, was effectively reversed by CBDA. Activator protein-1 (AP-1)-driven transcriptional activity directly involved in the regulation of COX-2 was abrogated by the PPARβ/δ-specific inverse agonists (GSK0660/ST-247). Thus, it is implicated that there is positive interaction between PPARβ/δ and AP-1 in regulation of COX-2. These data support the concept that CBDA is a functional down-regulator of COX-2 through the abrogation of PPARβ/δ-related signaling, at least in part, in MDA-MB-231 cells.

著者

West Brett J. Su Chen X. C. Jarakae Jensen

出版者

The Japanese Society of Toxicology

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.34, no.5, pp.581-585, 2009-10-01 (Released:2009-10-01)

参考文献数

15

被引用文献数

24 31

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Morinda citrifolia (noni) fruit juice has been approved as a safe food in many nations. A few cases of hepatitis in people who had been drinking noni juice have been reported, even though no causal link could be established between the liver injury and ingestion of the juice. To more fully evaluate the hepatotoxic potential of noni fruit juice, in vitro hepatotoxicity tests were conducted in human liver cells, HepG2 cell line. A subchronic oral toxicity test of noni fruit was also performed in Sprague-Dawley (SD) rats to provide benchmark data for understanding the safety of noni juice, without the potential confounding variables associated with many commercial noni juice products. Freeze-dried filtered noni fruit puree did not decrease HepG2 cell viability or induce neutral lipid accumulation and phospholipidosis. There were no histopathological changes or evidence of dose-responses in hematological and clinical chemistry measurements, including liver function tests. The no-observed-adverse-effect level (NOAEL) for freeze-dried noni fruit puree is greater than 6.86 g/kg body weight, equivalent to approximately 90 ml of noni fruit juice/kg. These findings corroborate previous conclusions that consumption of noni fruit juice is unlikely to induce adverse liver effects.

著者

Hyo Jin Kang Young Bin Hong Yong Weon Yi Chi-Heum Cho Antai Wang Insoo Bae

出版者

日本毒性学会

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.38, no.3, pp.355-361, 2013-06-01 (Released:2013-05-11)

参考文献数

29

被引用文献数

6 11

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The risk factors for breast cancer, the most common female malignant cancer, include environmental factors such as radiation, tobacco, a high-fat diet, and xenoestrogens as well as hormones. In addition, BRCA1 and BRCA2 are the most well-known genetic factors that increase risk for breast cancer. Coincidence of those environmental and genetic factors might augment the risk of tumorigenesis of breast. To verify this hypothesis, we briefly evaluated the carcinogenic potency of various environmental factors in the absence or presence of BRCA1 as a genetic factor in a normal mammary epithelial cell line, MCF10A. Many environmental factors tested increased cellular ROS level in the absence of other insult. In addition, TCDD, DMBA, 3MC, and BPA enhanced the BaP-induced ROS production. BRCA1 knockdown (BRCA1-KD) cells by siRNA significantly induced cellular accumulation of ROS compared to control cells. In this setting, the addition of paraquat, TCDD, DMBA, 2OHE2 or 4OHE2 significantly augmented ROS generation in BRCA1-KD MCF10A cells. Measurements of BaP-DNA adduct formation as a marker of DNA damage also revealed that BRCA1 deficiency leads increased DNA damage. In addition, TCDD and DMBA significantly increased BaP-DNA adduct formation in the absence of BRCA1. These results imply that elevated level of ROS is correlated with increase of DNA damage in BRCA1 defective cells. Taken together, our study suggests that several environmental factors might increase the risk of tumorigenesis in BRCA1 defective breast epithelial cells.

著者

Galen Guo Emmanuel Yumvihoze Alexandre J. Poulain Hing Man Chan

出版者

The Japanese Society of Toxicology

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.43, no.12, pp.717-725, 2018 (Released:2018-12-04)

参考文献数

45

被引用文献数

22

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Monomethylmercury (MMHg) is a potent neurotoxicant that can be bioaccumulated and biomagnified through trophic levels. Human populations whose diets contain MMHg are at risk of MMHg toxicity. The gut microbiota was identified as a potential factor causing variation in MMHg absorption and body burden. However, little is known about the role of gut microbiota on Hg transformations. We conducted a series of in vitro experiments to study the effects of dietary nutrient change on Hg metabolism and the human gut microbiota using anoxic fecal slurry incubations. We used stable Hg isotope tracers to track MMHg production and degradation and characterized the microbiota using high throughput sequencing of the 16S rRNA gene. We show that the magnitude of MMHg degradation is individual dependent and rapidly responds to changes in nutrient amendments, leading to complete degradation of the MMHg present. Although the mechanism involved remains unknown, it does not appear to involve the well-known mer operon. Our data are the first to show a nutrient dependency on the ability of the simulated human gut microbiota to demethylate MMHg. This work provides much-needed insights into individual variations in Hg absorption and potential toxicity.

著者

Nozomi Asaoka Hiroyuki Kawai Naoya Nishitani Haruko Kinoshita Norihiro Shibui Kazuki Nagayasu Hisashi Shirakawa Shuji Kaneko

出版者

日本毒性学会

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.41, no.6, pp.813-816, 2016-12-01 (Released:2016-11-16)

参考文献数

16

被引用文献数

12

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N-[[1-(5-fluoropentyl)-1H-indazol-3-yl]carbonyl]-3-methyl-D-valine methyl ester (5F-ADB) is one of the most potent synthetic cannabinoids and elicits severe psychotic symptoms in humans, sometimes causing death. To investigate the neuronal mechanisms underlying its toxicity, we examined the effects of 5F-ADB on midbrain dopaminergic and serotonergic systems, which modulate various basic brain functions such as those in reward-related behavior. 5F-ADB-induced changes in spontaneous firing activity of dopaminergic and serotonergic neurons were recorded by ex vivo electrophysiological techniques. In dopaminergic neurons, 5F-ADB (1 μM) significantly increased the spontaneous firing rate, while 5F-ADB failed to activate dopaminergic neurons in the presence of the CB1 antagonist AM251 (1 μM). However, the same concentration of 5F-ADB did not affect serotonergic-neuron activity. These results suggest that 5F-ADB activates local CB1 receptors and potentiates midbrain dopaminergic systems with no direct effects on midbrain serotonergic systems.

著者

Asuka Kaizaki Sachiko Tanaka Satoshi Numazawa

出版者

日本毒性学会

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.39, no.1, pp.1-6, 2014-02-01 (Released:2014-01-10)

参考文献数

23

被引用文献数

19 56

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1-phenyl-2-(1-pyrrolidinyl)-1-pentanone (α-PVP) is a new designer drug of the cathinone type. People who have taken drugs containing α-PVP or other synthetic cathinone reportedly lose consciousness, develop difficulty breathing, and at worst case, die. However, the mechanism underlying α-PVP-induced neurotoxicity is unknown. The objective of the present study was to investigate the effect of α-PVP on the central nervous system (CNS) and compare its neurotoxicity with that of methamphetamine (METH) in mice. Balb/c male mice (8 weeks old) were orally administered α-PVP (25 mg/kg) or METH (5 mg/kg). α-PVP induced a significant increase in locomotor activity, which occurred earlier than locomotor activity induced by METH. This increase was inhibited by the D1 receptor antagonist SCH23990 (50 µg/kg, i.p.) and the D2 receptor antagonist sulpiride (50 mg/kg, i.m.). The extracellular concentration of dopamine (DA) in the striatum, determined by in vivo microdialysis increased immediately after α-PVP administration. These results suggest that α-PVP stimulates DA release, causing an increase in locomotor activity, and that this stimulatory effect of α-PVP on CNS is mediated, at least in part, by the D1 and D2 receptors.

著者

Jun Kanno

出版者

日本毒性学会

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.41, no.Special, pp.SP105-SP109, 2016-12-31 (Released:2017-04-11)

参考文献数

15

被引用文献数

21

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Silent Spring by Rachel Carson (1962) established a role for environmental chemicals in cancer and Our Stolen Future by Theo Colbone, Dianne Dumanoski and John Peterson Myers (1996) coined the concept of “Endocrine Disrupting Chemicals (EDCs)” with its mechanistic plausibility for all the living organisms. For basic biologists, seeing a non-monotonic dose-response curve was a matter of course. In contrast, for the toxicologists at that time, the dose-response curves should be monotonic. It took some time for toxicologists to accept the plausibility that animals and humans are subject to the effects of EDCs act in a way that is explained by the new paradigm of receptor-mediated toxicity or in other words “signal toxicity.” In classical toxicology, a toxic substance reaches a cellular target and induces malfunction. The target molecules are proteins including enzymes, lipid membranes, DNA, and other components of the cell which are damaged by the toxic substances. On the other hand, in the case of signal toxicity, a chemical binds to a specific receptor - after that, the chemical itself is not important. The signal from the receptor initiates a cascade of molecular events that leads to various changes in the cells and organs. When the signal is abnormal for a cell or an organ in terms of quality, intensity and timing, then the signal will induce adverse effects to the target. An extreme example of signal toxicity is the 1981 Nobel Prize in Physiology or Medicine work by Drs. Hubel and Wiesel. They blocked the signal of sharp images from the retina to the brain and found that the visual cortex needed this signal at the correct time for its proper development. In humans, such signal disruption is well known to induce “form-deprivation amblyopia” in infants. The concept of signal toxicity widens the range of systems vulnerable to EDCs and facilitates the understanding of their biological characteristics. For example, compared with intrinsic ligands, xenobiotic chemicals usually act as weak agonists and/or weak antagonists of receptor systems; the dose-response characteristics and the dose range will depend on the signaling system of concern. If the signal is used for organogenesis and functional maturation, there would be a critical period in the development during which the disturbance of such signals may cause irreversible changes. Since recepter-based signaling mechanisms are usually an amplification systems, it is hard to set a threshold in its dose response, and the outcome of signal toxicity is often stochastic at low doses. This review attempts to explain the benefits of incorporating the concept of signal toxicology for widening the range of toxicology for the better protection of human and environmental health in modern civilized life, where chemicals are designed to be less toxic in terms of traditional toxicity but not yet in “signal toxicity.”

著者

Natsumi Seki Masahiro Akiyama Hiroto Yamakawa Koji Hase Yoshito Kumagai Yun-Gi Kim

出版者

The Japanese Society of Toxicology

雑誌

The Journal of Toxicological Sciences (ISSN:03881350)

巻号頁・発行日

vol.46, no.2, pp.91-97, 2021 (Released:2021-02-02)

参考文献数

29

被引用文献数

5 12

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Methylmercury (MeHg), an environmental electrophile, binds covalently to the cysteine residues of proteins in organs, altering protein function and causing cytotoxicity. MeHg has also been shown to alter the composition of gut microbes. The gut microbiota is a complex community, the disturbance of which has been linked to the development of certain diseases. However, the relationship between MeHg and gut bacteria remains poorly understood. In this study, we showed that MeHg binds covalently to gut bacterial proteins via cysteine residues. We examined the effects of MeHg on the growth of selected Lactobacillus species, namely, L. reuteri, L. gasseri, L. casei, and L. acidophilus, that are frequently either positively or negatively correlated with human diseases. The results revealed that MeHg inhibits the growth of Lactobacillus to varying degrees depending on the species. Furthermore, the growth of L. reuteri, which was inhibited by MeHg exposure, was restored by Na2S2 treatment. By comparing mice with and without gut microbiota colonization, we found that gut bacteria contribute to the production of reactive sulfur species such as hydrogen sulfide and hydrogen persulfide in the gut. We also discovered that the removal of gut bacteria accelerated accumulation of mercury in the cerebellum, liver, and lungs of mice subsequent to MeHg exposure. These results accordingly indicate that MeHg is captured and inactivated by the hydrogen sulfide and hydrogen persulfide produced by intestinal microbes, thereby providing evidence for the role played by gut microbiota in reducing MeHg toxicity.