Efeitos tóxicos dos sedimentos do estuário do rio Capibaribe em embriões de zebrafish (Danio rerio) / Toxic effects of sediments of the Capibaribe estuary on zebrafish embryos (Danio rerio)

O presente estudo utilizou embriões de Danio rerio expostos aos elutriatos dos sedimentos estuarinos do rio Capibaribe, dos períodos chuvoso e seco, e analisou os efeitos letais, teratogênicos, bem como a frequência cardíaca. Os testes de toxicidade com os embriões seguiram as diretrizes da OECD 236. Mediante os resultados obtidos, a frequência cardíaca e a teratogenicidade foram os efeitos mais observados nos animais quando submetidos às amostras. Entre os efeitos teratogênicos, o retardo geral no desenvolvimento dos embriões foi o mais frequente durante as análises. Tais efeitos tóxicos se modificaram entre os pontos e entre os períodos de coleta. Essa variação de toxicidade pode estar relacionada à diversidade de atividades realizadas no entorno desse estuário, a influência do regime de chuvas, marés e correntes, indicando que a análise dos efeitos subletais e da teratogenicidade em embriões de D. rerio constitui bom parâmetro para avaliações de toxicidade de amostras ambientais.(AU)

The present study used Danio rerio embryos exposed to the elutriates of the estuarine sediments of the Rio Capibaribe, from the rainy and dry periods, where the lethal effects, teratogenic and heart rate were analyzed. Embryotoxicity tests followed the guidelines of OECD 236. Based on the results obtained, heart rate and teratogenicity demonstrated higher sensitivity to the samples. Among the teratogenic effects, the general delay in embryo development was the most frequent effect during the analyzes. These toxic effects changed between the points and between the collection periods. This variation of toxicity may be related to the diversity of activities carried out around this estuary, the influence of rainfall, tides, and currents, indicating the analysis of sublethal effects and teratogenicity in the D. rerio embryos are useful parameters for toxic evaluation of environmental samples.(AU)

Efeitos tóxicos dos sedimentos do estuário do rio Capibaribe em embriões de zebrafish (Danio rerio) / Toxic effects of sediments of the Capibaribe estuary on zebrafish embryos (Danio rerio)

O presente estudo utilizou embriões de Danio rerio expostos aos elutriatos dos sedimentos estuarinos do rio Capibaribe, dos períodos chuvoso e seco, e analisou os efeitos letais, teratogênicos, bem como a frequência cardíaca. Os testes de toxicidade com os embriões seguiram as diretrizes da OECD 236. Mediante os resultados obtidos, a frequência cardíaca e a teratogenicidade foram os efeitos mais observados nos animais quando submetidos às amostras. Entre os efeitos teratogênicos, o retardo geral no desenvolvimento dos embriões foi o mais frequente durante as análises. Tais efeitos tóxicos se modificaram entre os pontos e entre os períodos de coleta. Essa variação de toxicidade pode estar relacionada à diversidade de atividades realizadas no entorno desse estuário, a influência do regime de chuvas, marés e correntes, indicando que a análise dos efeitos subletais e da teratogenicidade em embriões de D. rerio constitui bom parâmetro para avaliações de toxicidade de amostras ambientais.(AU)

The present study used Danio rerio embryos exposed to the elutriates of the estuarine sediments of the Rio Capibaribe, from the rainy and dry periods, where the lethal effects, teratogenic and heart rate were analyzed. Embryotoxicity tests followed the guidelines of OECD 236. Based on the results obtained, heart rate and teratogenicity demonstrated higher sensitivity to the samples. Among the teratogenic effects, the general delay in embryo development was the most frequent effect during the analyzes. These toxic effects changed between the points and between the collection periods. This variation of toxicity may be related to the diversity of activities carried out around this estuary, the influence of rainfall, tides, and currents, indicating the analysis of sublethal effects and teratogenicity in the D. rerio embryos are useful parameters for toxic evaluation of environmental samples.(AU)

Exposição crônica ao cloridrato de metformina e à glibenclamida causa alterações comportamentais, glicêmicas e de mortalidade em Hemigrammus caudovittatus e Danio rerio / Chronic exposure to metformin chloridrate and glibenclamide causes behavioral, blood glucose and mortality changes of Hemigrammus caudovittatus and Danio rerio

Hemigrammus caudovittatus e Danio rerio foram expostos aos hipoglicemiantes orais (HOs) cloridrato de metformina a 40µg/L e 120µg/L e glibenclamida a 0,13µg/L e 0,39µg/L durante 100 dias. Foram avaliados os efeitos tóxicos dos fármacos em relação ao peso, ao comportamento animal, à glicemia e à mortalidade. H. caudovittatus expostos à menor concentração dos fármacos apresentaram aumento significativo (P<0,05) no evento Respiração Aérea. Ainda, foi observado aumento no comportamento Descansar quando os animais foram expostos à glibenclamida a 0,39µg/L. Em D. rerio expostos ao cloridrato de metformina a 120µg/L, foi observado aumento (P<0,05) no comportamento Descansar. A glibenclamida provocou redução (P<0,05) na glicemia de H. caudovittatus. Ambos os fármacos causaram efeito letal na espécie D. rerio, contudo a glibenclamida foi mais tóxica, causando 100% de mortalidade em 30 dias de exposição. Os animais que vieram a óbito apresentaram congestão nos arcos branquiais e hemorragia. Os HOs foram desenvolvidos para apresentarem efeitos fisiológicos em mamíferos, entretanto efeitos tóxicos foram encontrados nas duas espécies de peixe estudadas. Isso levanta a preocupação sobre possíveis efeitos tóxicos de HOs e sobre quais métodos serão utilizados para a sua degradação no ambiente aquático.(AU)

Hemigrammus caudovittatus and Danio rerio were exposed to oral hypoglycemic drugs (HOs) metformin hydrochloride at 40µg/L and 120µg/L and to glibenclamide at 0.13µg/L and 0.39µg/L during 100 days. Toxic effects of the drugs were evaluated based on weight, animal behavior, blood glucose and mortality. H. caudovittatus exposed to lowest concentration of the drugs showed significant increase (P< 0.05) in the Air breathing event. Furthermore, increase in Rest event was observed when animals were exposed to glibenclamide at 0.39µg/L. An increase (P< 0.05) in the frequency of Rest behavior in the D. rerio exposed to metformin hydrochloride at 120µg/L was observed. Glibenclamide caused decrease (P< 0.05) in the blood glucose of H. caudovittatus. Both drugs caused lethal effect against D. rerio. Nevertheless, glibenclamide was more toxic causing 100% of mortality after 30 days of exposure. The animals that died showed congestion on the branchial arches and hemorrhage. The HOs were developed to have physiological effects in mammals. However, toxic effects were found in both species of fish studied. This raises concerns about possible toxic effects of HOs and what methods will be used for their degradation in the aquatic environment.(AU)

Exposição crônica ao cloridrato de metformina e à glibenclamida causa alterações comportamentais, glicêmicas e de mortalidade em Hemigrammus caudovittatus e Danio rerio / Chronic exposure to metformin chloridrate and glibenclamide causes behavioral, blood glucose and mortality changes of Hemigrammus caudovittatus and Danio rerio

Hemigrammus caudovittatus e Danio rerio foram expostos aos hipoglicemiantes orais (HOs) cloridrato de metformina a 40µg/L e 120µg/L e glibenclamida a 0,13µg/L e 0,39µg/L durante 100 dias. Foram avaliados os efeitos tóxicos dos fármacos em relação ao peso, ao comportamento animal, à glicemia e à mortalidade. H. caudovittatus expostos à menor concentração dos fármacos apresentaram aumento significativo (P<0,05) no evento Respiração Aérea. Ainda, foi observado aumento no comportamento Descansar quando os animais foram expostos à glibenclamida a 0,39µg/L. Em D. rerio expostos ao cloridrato de metformina a 120µg/L, foi observado aumento (P<0,05) no comportamento Descansar. A glibenclamida provocou redução (P<0,05) na glicemia de H. caudovittatus. Ambos os fármacos causaram efeito letal na espécie D. rerio, contudo a glibenclamida foi mais tóxica, causando 100% de mortalidade em 30 dias de exposição. Os animais que vieram a óbito apresentaram congestão nos arcos branquiais e hemorragia. Os HOs foram desenvolvidos para apresentarem efeitos fisiológicos em mamíferos, entretanto efeitos tóxicos foram encontrados nas duas espécies de peixe estudadas. Isso levanta a preocupação sobre possíveis efeitos tóxicos de HOs e sobre quais métodos serão utilizados para a sua degradação no ambiente aquático.(AU)

Hemigrammus caudovittatus and Danio rerio were exposed to oral hypoglycemic drugs (HOs) metformin hydrochloride at 40µg/L and 120µg/L and to glibenclamide at 0.13µg/L and 0.39µg/L during 100 days. Toxic effects of the drugs were evaluated based on weight, animal behavior, blood glucose and mortality. H. caudovittatus exposed to lowest concentration of the drugs showed significant increase (P< 0.05) in the Air breathing event. Furthermore, increase in Rest event was observed when animals were exposed to glibenclamide at 0.39µg/L. An increase (P< 0.05) in the frequency of Rest behavior in the D. rerio exposed to metformin hydrochloride at 120µg/L was observed. Glibenclamide caused decrease (P< 0.05) in the blood glucose of H. caudovittatus. Both drugs caused lethal effect against D. rerio. Nevertheless, glibenclamide was more toxic causing 100% of mortality after 30 days of exposure. The animals that died showed congestion on the branchial arches and hemorrhage. The HOs were developed to have physiological effects in mammals. However, toxic effects were found in both species of fish studied. This raises concerns about possible toxic effects of HOs and what methods will be used for their degradation in the aquatic environment.(AU)

Potassium chloride and sodium chloride as reference toxicants to assess quality of toxicity tests carried out with the microcrustacean cladocera Ceriodaphnia dubia / Cloreto de potássio e cloreto de sódio como substâncias de referência para avaliar a qualidade do teste de toxicidade com o microcrustáceo cladocera Ceriodaphnia dubia

Two reference toxicants (potassium chloride-KCl and sodium chloride-NaCl) were used in the present study in order to assess the sensitivity of the microcrustacean cladocera Ceriodaphnia dubia. Chronic toxicity tests were carried out with those two salts and the sensitivity expressed as IC50;7D - concentration that causes inhibition of 50% of reproduction ability, in seven days exposure time. The medium values estimated for IC50;7D were 200.70 and 499.60 to KCl and NaCl, respectively. Those data have demonstrated that KCl can be more restrictive and more suitable than NaCl, when used as standard reference toxicant for plotting control charts of sensitivity.

No presente estudo foram utilizadas duas substâncias de referência (cloreto de potássio-KCl e cloreto de sódio-NaCl), para avaliar a sensibilidade do microcrustáceos cladocera Ceriodaphnia dubia. Testes de toxicidade crônica foram realizados com esses dois sais e a sensibilidade expressa como IC50;7D - concentração que causa inibição de 50% da capacidade de reprodução, em sete dias de tempo de exposição. Os valores médios estimados para IC50;7D foram 200,70 e 499,60 para KCl e NaCl, respectivamente. Esses resultados demonstraram que o KCl pode ser mais restritivo e mais adequado do que o NaCl, quando utilizado como substância de referência padrão para traçar gráficos de controle de sensibilidade.

Potassium chloride and sodium chloride as reference toxicants to assess quality of toxicity tests carried out with the microcrustacean cladocera Ceriodaphnia dubia / Cloreto de potássio e cloreto de sódio como substâncias de referência para avaliar a qualidade do teste de toxicidade com o microcrustáceo cladocera Ceriodaphnia dubia

Two reference toxicants (potassium chloride-KCl and sodium chloride-NaCl) were used in the present study in order to assess the sensitivity of the microcrustacean cladocera Ceriodaphnia dubia. Chronic toxicity tests were carried out with those two salts and the sensitivity expressed as IC50;7D - concentration that causes inhibition of 50% of reproduction ability, in seven days exposure time. The medium values estimated for IC50;7D were 200.70 and 499.60 to KCl and NaCl, respectively. Those data have demonstrated that KCl can be more restrictive and more suitable than NaCl, when used as standard reference toxicant for plotting control charts of sensitivity.(AU)

No presente estudo foram utilizadas duas substâncias de referência (cloreto de potássio-KCl e cloreto de sódio-NaCl), para avaliar a sensibilidade do microcrustáceos cladocera Ceriodaphnia dubia. Testes de toxicidade crônica foram realizados com esses dois sais e a sensibilidade expressa como IC50;7D - concentração que causa inibição de 50% da capacidade de reprodução, em sete dias de tempo de exposição. Os valores médios estimados para IC50;7D foram 200,70 e 499,60 para KCl e NaCl, respectivamente. Esses resultados demonstraram que o KCl pode ser mais restritivo e mais adequado do que o NaCl, quando utilizado como substância de referência padrão para traçar gráficos de controle de sensibilidade.(AU)

Non-neurotoxic activity of Malayan krait (Bungarus candidus) venom from Thailand

Background: Envenoming by kraits (genus Bungarus) is a medically significant issue in South Asia and Southeast Asia. Malayan krait (Bungarus candidus) venom is known to contain highly potent neurotoxins. In recent years, there have been reports on the non-neurotoxic activities of krait venom that include myotoxicity and nephrotoxicity. However, research on such non-neurotoxicity activities of Malayan krait venom is extremely limited. Thus, the aim of the present study was to determine the myotoxic, cytotoxic and nephrotoxic activities of B. candidus venoms from northeastern (BC-NE) and southern (BC-S) Thailand in experimentally envenomed rats. Methods: Rats were administered Malayan krait (BC-NE or BC-S) venom (50 g/kg, i.m.) or 0.9% NaCl solution (50 L, i.m.) into the right hind limb. The animals were sacrificed 3, 6 and 24 h after venom administration. The right gastrocnemius muscle and both kidneys were collected for histopathological analysis. Blood samples were also taken for determination of creatine kinase (CK) and lactate dehydrogenase (LDH) levels. The human embryonic kidney cell line (HEK-293) was used in a cell proliferation assay to determine cytotoxic activity. Results: Administration of BC-NE or BC-S venom (50 g/kg, i.m.) caused time-dependent myotoxicity, characterized by an elevation of CK and LDH levels. Histopathological examination of skeletal muscle displayed marked muscle necrosis and myofiber disintegration 24 h following venom administration. Both Malayan krait venoms also induced extensive renal tubular injury with glomerular and interstitial congestion in rats. BC-NE and BC-S venoms (1000.2 g/ mL) caused concentration-dependent cytotoxicity on the HEK-293 cell line. However, BC-NE venom (IC50 =8 ± 1 g/mL; at 24 h incubation; n = 4) was found to be significantly more cytotoxic than BC-S venom (IC50 =15 ± 2 g/mL; at 24 h incubation; n = 4). In addition, the PLA2 activity of BC-NE venom was significantly higher than that of BC-S venom...(AU)

Non-neurotoxic activity of Malayan krait (Bungarus candidus) venom from Thailand

Background: Envenoming by kraits (genus Bungarus) is a medically significant issue in South Asia and Southeast Asia. Malayan krait (Bungarus candidus) venom is known to contain highly potent neurotoxins. In recent years, there have been reports on the non-neurotoxic activities of krait venom that include myotoxicity and nephrotoxicity. However, research on such non-neurotoxicity activities of Malayan krait venom is extremely limited. Thus, the aim of the present study was to determine the myotoxic, cytotoxic and nephrotoxic activities of B. candidus venoms from northeastern (BC-NE) and southern (BC-S) Thailand in experimentally envenomed rats. Methods: Rats were administered Malayan krait (BC-NE or BC-S) venom (50 g/kg, i.m.) or 0.9% NaCl solution (50 L, i.m.) into the right hind limb. The animals were sacrificed 3, 6 and 24 h after venom administration. The right gastrocnemius muscle and both kidneys were collected for histopathological analysis. Blood samples were also taken for determination of creatine kinase (CK) and lactate dehydrogenase (LDH) levels. The human embryonic kidney cell line (HEK-293) was used in a cell proliferation assay to determine cytotoxic activity. Results: Administration of BC-NE or BC-S venom (50 g/kg, i.m.) caused time-dependent myotoxicity, characterized by an elevation of CK and LDH levels. Histopathological examination of skeletal muscle displayed marked muscle necrosis and myofiber disintegration 24 h following venom administration. Both Malayan krait venoms also induced extensive renal tubular injury with glomerular and interstitial congestion in rats. BC-NE and BC-S venoms (1000.2 g/ mL) caused concentration-dependent cytotoxicity on the HEK-293 cell line. However, BC-NE venom (IC50 =8 ± 1 g/mL; at 24 h incubation; n = 4) was found to be significantly more cytotoxic than BC-S venom (IC50 =15 ± 2 g/mL; at 24 h incubation; n = 4). In addition, the PLA2 activity of BC-NE venom was significantly higher than that of BC-S venom...

Utilização de métodos alternativos à experimentação animal em pesquisa / Use of alternative methods to animal testing in research

Para sobreviver em um ambiente adverso, o ser humano sempre contou com o auxílio dos animais para as mais variadas funções e finalidades. Quando trata-se de avaliação da toxicidade de uma substância é necessário verificar os efeitos nocivos que a mesma pode desencadear aos homens, animais e ambiente após exposição. Para que se possa verificar tal propósito, o modelo animal ainda tem sido o mais utilizado nos estudos de avaliação toxicológica. Entretanto, a utilização de animais na pesquisa é um tema que tem sido razão de diversas discussões e envolve a quantidade de animais utilizados, a real necessidade de sua utilização e a eficácia da extrapolação dos dados obtidos para seres humanos por exemplo. Por outro lado, pesquisadores e a comunidade científica nacional e internacional têm somado investimentos e esforços no desenvolvimento e validação de métodos alternativos ao uso de animais. Neste contexto, o conceito e uso dos 3 Rs, do inglês (Replace, Reduce e Refine), tornou-se tendência na avaliação da toxicidade de compostos. Desta forma, o presente trabalho apresenta em forma de revisão de literatura baseada em artigos publicados e atualizados, uma reflexão e uma abordagem atual acerca do tema sobre a relação do uso de animais em pesquisa e sua relevância para o avanço na avaliação do risco à exposição aos compostos químicos e aborda os métodos alternativos já implantados, bem como relaciona dados sobre a regulamentação na experimentação animal em nosso país.

In order to survive in an adverse environment, the human being has always had theassistance of animals for a variety of functions and purposes. Regarding the toxicityevaluation of a substance, it is necessary to check the harmful effects that it can generateto the human beings, animals and the environment after exposure. In order toverify this purpose, the animal model has been the most used in toxicological studiesso far. However, the use of animals in research is a topic that has brought heateddiscussion, which involves the number of animals used, the actual need for its use andeffectiveness of extrapolation of data obtained for humans for instance. On the otherhand, researchers and the national and international scientific community have doneinvestments and intensified efforts in the development and validation of alternativemethods to animal use. In this context the concept and use of the 3 R’s (Replace,Reduce and Refine), has become a trend in assessing the toxicity of compounds.Thus, this work presents in the form of a literature review a modern approach to thesubject of the relationship of the use of animals in research and its relevance to theadvance in risk assessment for exposure to chemical compounds. Besides that, thiswork discusses alternative methods already in place and relates data to the regulationon animal testing in our country.

Utilização de métodos alternativos à experimentação animal em pesquisa / Use of alternative methods to animal testing in research

Para sobreviver em um ambiente adverso, o ser humano sempre contou com o auxílio dos animais para as mais variadas funções e finalidades. Quando trata-se de avaliação da toxicidade de uma substância é necessário verificar os efeitos nocivos que a mesma pode desencadear aos homens, animais e ambiente após exposição. Para que se possa verificar tal propósito, o modelo animal ainda tem sido o mais utilizado nos estudos de avaliação toxicológica. Entretanto, a utilização de animais na pesquisa é um tema que tem sido razão de diversas discussões e envolve a quantidade de animais utilizados, a real necessidade de sua utilização e a eficácia da extrapolação dos dados obtidos para seres humanos por exemplo. Por outro lado, pesquisadores e a comunidade científica nacional e internacional têm somado investimentos e esforços no desenvolvimento e validação de métodos alternativos ao uso de animais. Neste contexto, o conceito e uso dos 3 Rs, do inglês (Replace, Reduce e Refine), tornou-se tendência na avaliação da toxicidade de compostos. Desta forma, o presente trabalho apresenta em forma de revisão de literatura baseada em artigos publicados e atualizados, uma reflexão e uma abordagem atual acerca do tema sobre a relação do uso de animais em pesquisa e sua relevância para o avanço na avaliação do risco à exposição aos compostos químicos e aborda os métodos alternativos já implantados, bem como relaciona dados sobre a regulamentação na experimentação animal em nosso país.(AU)

In order to survive in an adverse environment, the human being has always had theassistance of animals for a variety of functions and purposes. Regarding the toxicityevaluation of a substance, it is necessary to check the harmful effects that it can generateto the human beings, animals and the environment after exposure. In order toverify this purpose, the animal model has been the most used in toxicological studiesso far. However, the use of animals in research is a topic that has brought heateddiscussion, which involves the number of animals used, the actual need for its use andeffectiveness of extrapolation of data obtained for humans for instance. On the otherhand, researchers and the national and international scientific community have doneinvestments and intensified efforts in the development and validation of alternativemethods to animal use. In this context the concept and use of the 3 Rs (Replace,Reduce and Refine), has become a trend in assessing the toxicity of compounds.Thus, this work presents in the form of a literature review a modern approach to thesubject of the relationship of the use of animals in research and its relevance to theadvance in risk assessment for exposure to chemical compounds. Besides that, thiswork discusses alternative methods already in place and relates data to the regulationon animal testing in our country.(AU)

Cytotoxicity assays as tools to assess water quality in the Sinos River basin / Ensaios de citotoxicidade como ferramentas para avaliar a qualidade da água da bacia do Rio do Sinos

Cytotoxicity assays using cell cultures may be an alternative to assess biological toxicity of surface waters and may help to improve the control of water quality. This study compared two methods to prepare culture media for the exposure of Hep-2 cells to water samples collected from the Rolante River, an important affluent of the Sinos River. The toxicity was evaluated using the MTT and neutral red assays. Two methods were used to prepare culture media. In method 1, the sample was diluted at 1:1, 1:10, 1:100, 1:1000, 1:10.000 (v/v, sample/medium) in a standard culture medium; in method 2, water samples were used as the solvent for the culture medium, which was prepared at concentrations of 100, 80, 60, 40 and 20%. Semi-confluent cultures were then exposed to the media test for 24 hours, and cytotoxicity was determined immediately using the MTT and NR assays. Mitochondrial activity (MTT) was significantly lower at all concentrations in both methods, except at 1:1000 in method 1. However, the lysosome viability (NR) results revealed cytotoxicity only in the 1:1 sample of method 1. Both culture preparation methods were efficient and sensitive to the MTT assay, but method 2 seemed to be more adequate for the NR assay. The Rolante River has cytotoxic contaminants to Hep-2 cells, which may be one of the explanations for the poor water quality of the Sinos River basin.(AU)

Os ensaios de citotoxicidade utilizando culturas de células constituem uma alternativa para avaliar a toxicidade biológica de águas de superfície e podem auxiliar no controle da qualidade da água. Este estudo comparou dois métodos de preparação dos meios de cultura com amostras de água coletadas no rio Rolante, um importante afluente do Rio dos Sinos, para a exposição de células Hep-2. A toxicidade foi avaliada usando os ensaios do MTT e do vermelho neutro (VN). Dois métodos foram utilizados para preparar os meios de cultura. No método 1, a amostra foi diluída a 1:1, 1:10, 1:100, 1:1000 e 1:10.000 (v/v, amostra/ meio de cultivo) em um meio de cultura padrão; no método 2, as amostras de água foram utilizados como solventes para o meio de cultura, o qual foi preparado em concentração de 100% e nas diluições de 80, 60, 40 e 20%. Culturas semi-confluentes foram então expostas aos meios teste durante 24 horas, e a citotoxicidade foi determinada imediatamente usando os ensaios MTT e VN. A atividade mitocondrial (MTT) foi significativamente menor em todas as concentrações em ambos os métodos, exceto na diluição 1:1000 do método 1. No entanto, os resultados de viabilidade lisossomal (VN) revelaram citotoxicidade apenas no na diluição 1:1 do método 1. Ambos os métodos de preparação do meio cultura foram eficientes e sensíveis para o ensaio do MTT, mas o método 2 foi mais adequado para o ensaio do VN. O rio Rolante possui contaminantes citotóxicos para as células Hep-2, o que pode ser uma das explicações para a baixa qualidade da água da Bacia do Rio dos Sinos.(AU)

Exposure to 50 Hz electromagnetic field changes the efficiency of the scorpion alpha toxin

Background Extremely low-frequency (50 Hz) electromagnetic field (ELF-EMF) is produced by electric power transmission lines and electronic devices of everyday use. Some phenomena are proposed as first effects of ELF-EMF: the discrete changes in the membrane potential and the increase of the calcium channel activity as well as the intracellular concentration of Ca 2+ . Interaction of the scorpion alpha toxin with the sodium channel depends on the orientation of the charges and may be perturbed by changes in the membrane polarization. The toxin induces overexcitability in the nervous system and an increase in the neurotransmitters released with different consequences, mainly the paralysis of muscles. We assumed that the exposure to ELF-EMF 0.7 mT will change the effects of the insect selective scorpion alpha toxin (recombinant LqhIT from Leiurus quinquestriatus hebraeus) at the level of the cercal nerve function, the synaptic transmission and on the level of entire insect organism. Taking into account the compensatory mechanisms in organisms, we tested in addition ten times higher ELF-EMF on whole insects.Methods Experiments were performed in vivo on cockroaches (Periplaneta americana) and in vitro on isolated cockroach abdominal nerve cord with cerci. In biotests, the effects of LqhIT (10 8 M) were estimated on the basis of the insect ability to turn back from dorsal to ventral side. Three groups were compared: the control one and the two exposed to ELF-EMF 0.7 and 7 mT. Bioelectrical activity of the cercal nerve and of the connective nerve that leaves the terminal abdominal ganglion was recorded using extracellular electrodes. LqhIT (5 × 10 8 M) induced modifications of neuronal activity that were observed in the control cockroach preparations and in the ones exposed to ELF-EMF (0.7 mT). The exposure to ELF-EMF was carried out using coils with a size appropriate to the examined objects.Results The exposure to ELF-EMF (0.7 mT) modified the effects of LqhIT (5 × 108 M) on activity of the cercal nerve and of the connective nerve. We observed a decrease of the toxin effect on the cercal nerve activity, but the toxic effect of LqhIT on the connective nerve was increased. Biotests showed that toxicity of LqhIT (10 8 M) on cockroaches was reduced by the exposure to ELF-EMF (0.7 and 7 mT).Conclusions The exposure to 50 Hz ELF-EMF modified the mode of action of the anti-insect scorpion alpha toxin LqhIT at cellular level of the cockroach nervous system and in biotests. Toxin appeared as a usefull tool in distinguishing between the primary and the secondary effects of ELF-EMF.(AU)

Allosteric interactions between receptor site 3 and 4 of voltage-gated sodium channels: a novel perspective for the underlying mechanism of scorpion sting-induced pain

Background BmK I, a site-3-specific modulator of voltage-gated sodium channels (VGSCs), causes pain and hyperalgesia in rats, while BmK IT2, a site-4-specific modulator of VGSCs, suppresses pain-related responses. A stronger pain-related effect has been previously attributed to Buthus martensi Karsch (BmK) venom, which points out the joint pharmacological effect in the crude venom.Methods In order to detect the joint effect of BmK I and BmK IT2 on ND7-23 cells, the membrane current was measured by whole cell recording. BmK I and BmK IT2 were applied successively and jointly, and the synergistic modulations of VGSCs on ND7-23 cells were detected.Results Larger peak I Na and more negative half-activation voltage were elicited by joint application of BmK I and BmK IT2 than by application of BmK I or BmK IT2 alone. Compared to the control, co-applied BmK I and BmK IT2 also significantly prolonged the time constant of inactivation.Conclusions Our results indicated that site-4 toxin (BmK IT2) could enhance the pharmacological effect induced by site-3 toxin (BmK I), suggesting a stronger effect elicited by both toxins that alone usually exhibit opposite pharmacological effects, which is related to the allosteric interaction between receptor site 3 and site 4. Meanwhile, these results may bring a novel perspective for exploring the underlying mechanisms of scorpion sting-induced pain.(AU)

Exposure to 50 Hz electromagnetic field changes the efficiency of the scorpion alpha toxin

Background Extremely low-frequency (50 Hz) electromagnetic field (ELF-EMF) is produced by electric power transmission lines and electronic devices of everyday use. Some phenomena are proposed as first effects of ELF-EMF: the discrete changes in the membrane potential and the increase of the calcium channel activity as well as the intracellular concentration of Ca 2+ . Interaction of the scorpion alpha toxin with the sodium channel depends on the orientation of the charges and may be perturbed by changes in the membrane polarization. The toxin induces overexcitability in the nervous system and an increase in the neurotransmitters released with different consequences, mainly the paralysis of muscles. We assumed that the exposure to ELF-EMF 0.7 mT will change the effects of the insect selective scorpion alpha toxin (recombinant LqhIT from Leiurus quinquestriatus hebraeus) at the level of the cercal nerve function, the synaptic transmission and on the level of entire insect organism. Taking into account the compensatory mechanisms in organisms, we tested in addition ten times higher ELF-EMF on whole insects.Methods Experiments were performed in vivo on cockroaches (Periplaneta americana) and in vitro on isolated cockroach abdominal nerve cord with cerci. In biotests, the effects of LqhIT (10 8 M) were estimated on the basis of the insect ability to turn back from dorsal to ventral side. Three groups were compared: the control one and the two exposed to ELF-EMF 0.7 and 7 mT. Bioelectrical activity of the cercal nerve and of the connective nerve that leaves the terminal abdominal ganglion was recorded using extracellular electrodes. LqhIT (5 × 10 8 M) induced modifications of neuronal activity that were observed in the control cockroach preparations and in the ones exposed to ELF-EMF (0.7 mT). The exposure to ELF-EMF was carried out using coils with a size appropriate to the examined objects.Results The exposure to ELF-EMF (0.7 mT) modified the effects of LqhIT (5 × 108 M) on activity of the cercal nerve and of the connective nerve. We observed a decrease of the toxin effect on the cercal nerve activity, but the toxic effect of LqhIT on the connective nerve was increased. Biotests showed that toxicity of LqhIT (10 8 M) on cockroaches was reduced by the exposure to ELF-EMF (0.7 and 7 mT).Conclusions The exposure to 50 Hz ELF-EMF modified the mode of action of the anti-insect scorpion alpha toxin LqhIT at cellular level of the cockroach nervous system and in biotests. Toxin appeared as a usefull tool in distinguishing between the primary and the secondary effects of ELF-EMF.

Allosteric interactions between receptor site 3 and 4 of voltage-gated sodium channels: a novel perspective for the underlying mechanism of scorpion sting-induced pain

Background BmK I, a site-3-specific modulator of voltage-gated sodium channels (VGSCs), causes pain and hyperalgesia in rats, while BmK IT2, a site-4-specific modulator of VGSCs, suppresses pain-related responses. A stronger pain-related effect has been previously attributed to Buthus martensi Karsch (BmK) venom, which points out the joint pharmacological effect in the crude venom.Methods In order to detect the joint effect of BmK I and BmK IT2 on ND7-23 cells, the membrane current was measured by whole cell recording. BmK I and BmK IT2 were applied successively and jointly, and the synergistic modulations of VGSCs on ND7-23 cells were detected.Results Larger peak I Na and more negative half-activation voltage were elicited by joint application of BmK I and BmK IT2 than by application of BmK I or BmK IT2 alone. Compared to the control, co-applied BmK I and BmK IT2 also significantly prolonged the time constant of inactivation.Conclusions Our results indicated that site-4 toxin (BmK IT2) could enhance the pharmacological effect induced by site-3 toxin (BmK I), suggesting a stronger effect elicited by both toxins that alone usually exhibit opposite pharmacological effects, which is related to the allosteric interaction between receptor site 3 and site 4. Meanwhile, these results may bring a novel perspective for exploring the underlying mechanisms of scorpion sting-induced pain.

Indian scorpions collected in Karnataka: maintenance in captivity, venom extraction and toxicity studies

Background Maintenance of scorpions under laboratory conditions is ideal for long-term venom collection to explore the therapeutic applications of scorpion venom. Collection of venom by electrical stimulation requires a reliable stimulator and effective restrainer. Thus, the present study was conducted to develop a convenient method to maintain scorpions and to extract their venom for toxicity studies via a modified restrainer and stimulator. Methods Four different scorpion species were collected, among which three species were maintained in the laboratory in containers that mimic their natural habitat. Venom was extracted from Hottentotta rugiscutis by electrical stimulation at 8 V for 18 months and LD50 was estimated by the graphic method of Miller and Tainter. Results A total of 373 scorpions including Hottentotta rugiscutis, Hottentotta tamulus, Lychas tricarinatus and Heterometrus swammerdami were collected, identified and maintained successfully, achieving a 97 % survival rate. Hottentotta rugiscutis yielded 6.0 mL of venom by electrical stimulation. The LD50 of H. rugiscutis venom was estimated to be 3.02 mg/kg of body weight in female Swiss albino mice. Conclusions Scorpions were successfully maintained for 18 months. Herein we have also documented a simple, cost-effective method of venom extraction by electrical stimulation using a modified restrainer. Furthermore, Hottentotta rugiscutis was reported for the first time in Karnataka.(AU)

Pharmacological characterization of venoms from three theraphosid spiders: Poecilotheria regalis, Ceratogyrus darlingi and Brachypelma epicureanum

Background Tarantulas (Theraphosidae) represent an important source of novel biologically active compounds that target a variety of ion channels and cell receptors in both insects and mammals. In this study, we evaluate and compare the pharmacological activity of venoms from three taxonomically different theraphosid spiders bred in captivity: Poecilotheria regalis, an aggressive arboreal tarantula from southeastern India; Ceratogyrus darlingi, an aggressive tarantula from southern Africa; and Brachypelma epicureanum, a docile tarantula from the Yucatan dry forest of Mexico. Prior to this study, no research had been conducted with regard to the composition and pharmacological activity of these venoms. Methods The pharmacological characterization of the venoms was described for the first time by the assessment of their toxicity in crickets (LD50) along with their nociceptive (by using the formalin test), hyaluronidase, phospholipase A2, edematogenic and caseinolytic activity. Results P. regalis and B. epicureanum venoms induced a similar lethal effect on crickets (LD50 = 5.23 ± 3.1 and 14.4 ± 5.0 μg protein/g 48 h post-injection, respectively), whereas C. darlingi venom (119.4 ± 29.5 μg protein/g 48 h post-injection) was significantly less lethal than the other two venoms. All three venoms induced similar edematogenic activity on rats but did not induce nociceptive behavior. The assessment of enzymatic activity indicated that P. regalis venom induces significantly higher hyaluronidase activity (27.6 ± 0.9 TRU/mg) than both C. darlingi (99.7 ± 1.9 TRU/mg) and B. epicureanum (99.6 ± 1.6 TRU/mg); these latter venoms did not display phospholipase A2or caseinolytic activity. Conclusions This study demonstrates that these theraphosid spiders of different habitats produce venoms with different activities. P. regalis venom displays a high level of hyaluronidase activity, which may be associated with its potentially medically significant bite.(AU)

Pharmacological characterization of venoms from three theraphosid spiders: Poecilotheria regalis, Ceratogyrus darlingi and Brachypelma epicureanum

Background Tarantulas (Theraphosidae) represent an important source of novel biologically active compounds that target a variety of ion channels and cell receptors in both insects and mammals. In this study, we evaluate and compare the pharmacological activity of venoms from three taxonomically different theraphosid spiders bred in captivity: Poecilotheria regalis, an aggressive arboreal tarantula from southeastern India; Ceratogyrus darlingi, an aggressive tarantula from southern Africa; and Brachypelma epicureanum, a docile tarantula from the Yucatan dry forest of Mexico. Prior to this study, no research had been conducted with regard to the composition and pharmacological activity of these venoms. Methods The pharmacological characterization of the venoms was described for the first time by the assessment of their toxicity in crickets (LD50) along with their nociceptive (by using the formalin test), hyaluronidase, phospholipase A2, edematogenic and caseinolytic activity. Results P. regalis and B. epicureanum venoms induced a similar lethal effect on crickets (LD50 = 5.23 ± 3.1 and 14.4 ± 5.0 μg protein/g 48 h post-injection, respectively), whereas C. darlingi venom (119.4 ± 29.5 μg protein/g 48 h post-injection) was significantly less lethal than the other two venoms. All three venoms induced similar edematogenic activity on rats but did not induce nociceptive behavior. The assessment of enzymatic activity indicated that P. regalis venom induces significantly higher hyaluronidase activity (27.6 ± 0.9 TRU/mg) than both C. darlingi (99.7 ± 1.9 TRU/mg) and B. epicureanum (99.6 ± 1.6 TRU/mg); these latter venoms did not display phospholipase A2or caseinolytic activity. Conclusions This study demonstrates that these theraphosid spiders of different habitats produce venoms with different activities. P. regalis venom displays a high level of hyaluronidase activity, which may be associated with its potentially medically significant bite.

Indian scorpions collected in Karnataka: maintenance in captivity, venom extraction and toxicity studies

Background Maintenance of scorpions under laboratory conditions is ideal for long-term venom collection to explore the therapeutic applications of scorpion venom. Collection of venom by electrical stimulation requires a reliable stimulator and effective restrainer. Thus, the present study was conducted to develop a convenient method to maintain scorpions and to extract their venom for toxicity studies via a modified restrainer and stimulator. Methods Four different scorpion species were collected, among which three species were maintained in the laboratory in containers that mimic their natural habitat. Venom was extracted from Hottentotta rugiscutis by electrical stimulation at 8 V for 18 months and LD50 was estimated by the graphic method of Miller and Tainter. Results A total of 373 scorpions including Hottentotta rugiscutis, Hottentotta tamulus, Lychas tricarinatus and Heterometrus swammerdami were collected, identified and maintained successfully, achieving a 97 % survival rate. Hottentotta rugiscutis yielded 6.0 mL of venom by electrical stimulation. The LD50 of H. rugiscutis venom was estimated to be 3.02 mg/kg of body weight in female Swiss albino mice. Conclusions Scorpions were successfully maintained for 18 months. Herein we have also documented a simple, cost-effective method of venom extraction by electrical stimulation using a modified restrainer. Furthermore, Hottentotta rugiscutis was reported for the first time in Karnataka.

Implications of water hardness in ecotoxicological assessments for water quality regulatory purposes: a case study with the aquatic snail Biomphalaria glabrata (Say, 1818) / Implicações da dureza da água nas avaliações ecotoxicológicas com propósitos reguladores de qualidade da água: um estudo de caso com o caramujo aquático Biomphalaria glabrata

Water hardness is a property depending on the presence of alkaline earth metals, mainly calcium and magnesium. Among the strategies for water quality monitoring, ecotoxicological assays are performed to minimize impacts and classify water bodies. For these laboratory evaluations parameters are previously defined in the guidelines, including water hardness for both cultivation and testing medium. The present work was performed to evaluate the effects of different levels of water hardness on the survival and reproduction of the freshwater snail Biomphalaria glabrata and discuss the influence of natural water hardness on the results of ecotoxicological tests with these environmental samples. Comparing the groups it was possible to observe that those maintained in waters with least hardness had lower reproductive success, while the groups maintained in highest hardness showed better reproduction. These data show that waters with low hardness make the reproduction of the snail B. glabrata unfeasible, and this reveal a problem for ecotoxicity assays using natural water samples.

A dureza da água é uma propriedade dependente da presença de metais alcalino terrosos, principalmente cálcio e magnésio. Entre as estratégias para monitorar a qualidade da água ensaios ecotoxicológicos são realizados para minimizar impactos e classificar os corpos hídricos. Para essas avaliações em laboratório, parâmetros são previamente definidos nos protocolos, incluindo a dureza da água para cultivo e para a água de diluição. O presente trabalho foi realizado para avaliar os efeitos de diferentes níveis de dureza da água sobre a sobrevivência e a reprodução do caramujo de água doce Biomphalaria glabrata e discutir a influência da dureza de águas naturais nos resultados dos testes ecotoxicológicos com estas amostras ambientais. Comparando os grupos foi possível observar que aqueles mantidos em águas com menor dureza tiveram pior sucesso reprodutivo, enquanto os mantidos nas águas com maiores durezas tiveram melhor reprodução. Esses dados mostram que águas com baixas durezas tornam a reprodução do caramujo B. glabrata inviável, e esse fato revela-se como um problema para os ensaios ecotoxicológicos utilizando amostras de água naturais.