Lethal and sublethal responses in the fish, Odontesthes bonariensis, exposed to chlorpyrifos alone or under mixtures with endosulfán and lambda-cyhalothrin.

Need for ecotoxicological information on local species has been recently highlighted as a priority issue in Latin America. In addition, little information has been found on concentration distances between lethal and sublethal effects, and the effect of mixtures at these two levels of analysis. Chlorpyrifos (CPF) is an organophosphate insecticide broadly used in soybean crops which has dramatically expanded in Latin America and other regions of the world. The aim of the present study was to evaluate lethal and sublethal effects of CPF, singly or in mixtures, on the inland "Pejerrey" (Odontesthes bonariensis) under laboratory conditions. Bioassays were performed using 15-30 d post hatch Pejerrey larvae. Six toxicity tests were run for estimating the average inter-assay dose-response curve of CPF and other six for assessing the effects of mixtures of CPF with endosulfan (EN) or lambda-cyhalothrin (LC), at three toxic units (TU) proportions (25:75, 50:50, 75:25). In addition, four assays were performed to describe the average inter-assay dose-response inhibition curve of acetylcholinesterase (AchE) for CPF alone and two for assessing the mixtures. The estimated 96 h-LC50 for CPF was 2.26 ± 1.11 µg/L and the incipiency value was 0.048 ± 0.012 µg/L, placing this Neotropical species among the 13% of worldwide fish more sensitive to CPF. In addition, the 96 h-LC50 for EN and LC were 0.30 ± 0.012 µg/L and 0.043 ± 0.031 µg/L, respectively. Therefore, relative toxicity of the three soybean insecticides for O. bonariensis was LC > EN > CPF. Effects of mixtures with EN and LC were variable, but in general fitted to both, independent action (IA) and concentration addition (CA) models. Slight antagonism was found when CPF TU proportions were above 50%. Therefore, from the regulatory point of view, the use of both mixture models, CA or IA, would be precautionary. Differential sensitivity to CPF was found for AchE inhibition at the head (96 h-IC50 = 0.065 ± 0.058 µg/L) and the body (96 h-IC50 = 0.48 ± 0.17 µg/L). In addition, whereas no significant effects induced by mixtures was observed in body AchE activity, antagonism was induced in head AchE inhibition in presence of both, EN and LC in the mixture. The lethal to sublethal ratio was close to 25.2 and 3.4 when comparing the CPF-LC50 and IC50s for head and body AchE activity, respectively. However, considerable overlapping was observed between concentration-response curves, indicating that the use of AchE as biomarker for environmental monitoring would be limited.

Endoparasitic infections in dogs from rural areas in the Lobos District, Buenos Aires province, Argentina.

Dogs are definite hosts for several zoonotic helminthes and protozoan. Rural areas from the Lobos District in the northeast of Buenos Aires province, Argentina, are mainly used for livestock activity, increasing in this way the number of dogs on farms as well as the human risk of parasitic infections. The aims of this research were to evaluate the endoparasitic infections in dogs from farms in the Lobos District and analyze their zoonotic importance as well as several risk practices and habits of the rural population. Forty-two dog fecal samples obtained in 21 farms were analyzed through coproparasitological methods and coproantigen tests, which resulted in an overall parasite prevalence of 69.05% and 80.95% of the parasitized farms. The most frequent parasites were Trichuris vulpis and Eucoleus aerophila (26.19%), Echinococcus granulosus (19.05%), Uncinaria stenocephala and coccids (14.29%). The analysis of epidemiological files showed several habits of the rural population considered as risk factors associated with the presence of fecal samples parasitized and the presence of E. granulosus on the farms. It is clear that people involved with the farms studied were exposed to several helminthes that could cause serious diseases like cystic echinococcosis, which can become an important public health issue and affect the economy worldwide.

Endoparasitic infections in dogs from rural areas in the Lobos District, Buenos Aires province, Argentina / Infecçóes endoparasitas em cães de áreas rurais do distrito de Lobos, província de Buenos Aires, Argentina

Dogs are definite hosts for several zoonotic helminthes and protozoan. Rural areas from the Lobos District in the northeast of Buenos Aires province, Argentina, are mainly used for livestock activity, increasing in this way the number of dogs on farms as well as the human risk of parasitic infections. The aims of this research were to evaluate the endoparasitic infections in dogs from farms in the Lobos District and analyze their zoonotic importance as well as several risk practices and habits of the rural population. Forty-two dog fecal samples obtained in 21 farms were analyzed through coproparasitological methods and coproantigen tests, which resulted in an overall parasite prevalence of 69.05% and 80.95% of the parasitized farms. The most frequent parasites were Trichuris vulpis and Eucoleus aerophila (26.19%), Echinococcus granulosus (19.05%), Uncinaria stenocephala and coccids (14.29%). The analysis of epidemiological files showed several habits of the rural population considered as risk factors associated with the presence of fecal samples parasitized and the presence of E. granulosus on the farms. It is clear that people involved with the farms studied were exposed to several helminthes that could cause serious diseases like cystic echinococcosis, which can become an important public health issue and affect the economy worldwide.

Os cães são hospedeiros definitivos de vários helmintos e protozoários zoonóticos. As áreas rurais do distrito de Lobos, no nordeste da província de Buenos Aires, Argentina, destinam-se principalmente à atividade pecuária aumentando desta forma o número de cães em fazendas, bem como o risco humano de infecções parasitárias. Os objetivos desta pesquisa foram avaliar as infecções endoparasitas em cães de fazendas do distrito de Lobos e analisar a sua importância zoonótica, bem como as práticas de risco e hábitos da população rural. Quarenta e duas amostras de fezes de cães obtidos em 21 fazendas foram analisadas pelos métodos coproparasitológicos e testes de coproantígenos, resultando numa prevalência de parasitas de 69,05% e 80,95% das propriedades parasitados. Os parasitas mais frequentes foram Trichuris vulpis e Eucoleus aerophila (26,19%), Echinococcus granulosus (19,05%), Uncinaria stenocephala e coccídeos (14,29%). A análise dos arquivos epidemiológicos mostraram vários hábitos da população rural como fatores de risco associados com a presença de amostras fecais parasitadas e a presença de E. granulosus em propriedades rurais. É evidente que as pessoas das fazendas estudadas foram expostas a vários helmintos que podem causar doenças graves como equinococose cística, que constitui importante problema de saúde pública e econômico a nível mundial.

Memory impairment induced by IL-1beta is reversed by alpha-MSH through central melanocortin-4 receptors.

Interleukin-1beta (IL-1beta) significantly influences memory consolidation. Treatments that raise the level of IL-1beta in the brain, given after training, impair contextual fear conditioning. The melanocortin alpha-MSH exerts potent anti-inflammatory actions by physiologically antagonizing the effect of pro-inflammatory cytokines. Five subtypes of melanocortin receptors (MC1R-MC5R) have been identified, with MC3R and MC4R predominating in the central nervous system. The present experiments show that injection of IL-1beta (5 ng/0.25 microl) in dorsal hippocampus up to 15 min after training decreased freezing during the contextual fear test. The treatment with IL-1beta (5 ng/0.25 microl) 12h after conditioning cause amnesia when animals were tested 7 days post training. Thus, our results also demonstrated that IL-1beta can influence persistence of long-term memory. We determined that animals previously injected with IL-1beta can acquire a new contextual fear memory, demonstrating that the hippocampus was not damaged. Treatment with alpha-MSH (0.05 microg/0.25 microl) blocked the effect of IL-1beta on contextual fear memory. Administration of the MC4 receptor antagonist HS014 (0.5 microg/0.25 microl) reversed the effect of alpha-MSH. However, treatment with gamma-MSH (0.5 microg/0.25 microl), an MC3 agonist, did not affect IL-1beta-induced impairment of memory consolidation. These results suggest that alpha-MSH, through central MC4R can inhibit the effect of IL-1beta on memory consolidation.

Interleukin-1 beta-induced anorexia is reversed by ghrelin.

Interleukins, in particular interleukin-1beta (IL-1beta), reduce food intake after peripheral and central administration, which suggests that they contribute to anorexia during various infectious, neoplastic, and autoimmune diseases. On the other hand, ghrelin stimulates food intake by acting on the central nervous system (CNS) and is considered an important regulator of food intake in both rodents and humans. In the present study, we investigated if ghrelin could reverse IL-1beta-induced anorexia. Intracerebroventricular (i.c.v.) injection of 15, 30 or 45 ng/microl of IL-1beta caused significant suppression of food intake in 20 h fasting animals. This effect lasted for a 24h period. Ghrelin (0.15 nmol or 1.5 nmol/microl) produced a significant increase in cumulative food intake in normally fed animals. However, it did not alter food intake in 20 h fasting animals. Central administration of ghrelin reduced the anorexic effect of IL-1beta (15 ng/microl). The effect was observed 30 min after injection and lasted for the next 24h. This study provides evidence that ghrelin is an orexigenic peptide capable of antagonizing IL-1beta-induced anorexia.