Persistent impaired glucose metabolism in a zebrafish hyperglycemia model

AbstractDiabetes mellitus (DM) affects over 10% of the world's population. Hyperglycemia is the main feature for the diagnosis of this disease. The zebrafish (Danio rerio) is an established model organism for the study of various metabolic diseases. In this paper, hyperglycemic zebrafish, when immersed in a 111mM glucose solution for 14days, developed increased glycation of proteins from the eyes, decreased mRNA levels of insulin receptors in the muscle, and a reversion of high blood glucose level after treatment with anti-diabetic drugs (glimepiride and metformin) even after 7days of glucose withdrawal. Additionally, hyperglycemic zebrafish developed an impaired response to exogenous insulin, which was recovered after 7days of glucose withdrawal. These data suggest that the exposure of adult zebrafish to high glucose concentration is able to induce persistent metabolic changes probably underlined by a hyperinsulinemic state and impaired peripheral glucose metabolism

Acute Exposure to Microcystin-Producing Cyanobacterium Microcystis aeruginosa Alters Adult Zebrafish (Danio rerio) Swimming Performance Parameters

Microcystins (MCs) are toxins produced by cyanobacteria (blue-green algae), primarily Microcystis aeruginosa, forming water blooms worldwide. When an organism is exposed to environmental perturbations, alterations in normal behavioral patterns occur. Behavioral repertoire represents the consequence of a diversity of physiological and biochemical alterations. In this study, we assessed behavioral patterns and whole-body cortisol levels of adult zebrafish (Danio rerio) exposed to cell culture of the microcystin-producing cyanobacterium M. aeruginosa (MC-LR, strain RST9501). MC-LR exposure (100 μg/L) decreased by 63% the distance traveled and increased threefold the immobility time when compared to the control group. Interestingly, no significant alterations in the number of line crossings were found at the same MC-LR concentration and time of exposure. When animals were exposed to 50 and 100 μg/L, MC-LR promoted a significant increase (around 93%) in the time spent in the bottom portion of the tank, suggesting an anxiogenic effect. The results also showed that none of the MC-LR concentrations tested promoted significant alterations in absolute turn angle, path efficiency, social behavior, or whole-body cortisol level. These findings indicate that behavior is susceptible to MC-LR exposure and provide evidence for a better understanding of the ecological consequences of toxic algal blooms

Microcystin-LR acute exposure increases AChE activity via transcriptional ache activation in zebrafish (Danio rerio) brain

AbstractMicrocystins (MCs) constitute a family of cyanobacterial toxins, with more than 80 variants. These toxins are able to induce hepatotoxicity in several organisms mainly through the inhibition of protein phosphatases PP1 and PP2A and oxidative stress generation. Since recent evidence shows that MCs can either accumulate in brain or alter behavior patterns of fish species, in this study we tested the in vitro and in vivo effects of MC-LR at different concentrations on acetylcholinesterase (AChE) activity in zebrafish brain. In vivo studies showed that 100μg/L MC-LR led to a significant increase in the AChE activity (27%) when zebrafish were exposed to the toxin dissolved in water, but did not cause any significant changes when injected intraperitoneally. In addition, semiquantitative RT-PCR analysis demonstrated that 100μg/L MC-LR exposure also increased ache mRNA levels in zebrafish brain. The in vitro assays did not reveal any significant changes in AChE activity. These findings provide the first evidence that brain AChE is another potential target for MCs and suggest that the observed increases in AChE enzymatic activity and in ache transcript levels after MC-LR exposure depend, at least partially, on branchial uptake or ingestion

Mechanisms underlying the antiproliferative effects of a series of quinoxaline-derived chalcones

The present study aimed to characterize the effects of quinoxaline-derived chalcones, designed on the basis of the selective PI3Kγ inhibitor AS605240, in oral cancer cells. Three lead compounds, namely N9, N17 and N23, were selected from a series of 20 quinoxaline-derived chalcones, based on an initial screening using human and rat squamous cell carcinoma lineages, representing compounds with at least one methoxy radical at the A-ring. The selected chalcones, mainly N9 and N17, displayed marked antiproliferative effects, via apoptosis and autophagy induction, with an increase of sub-G1 population and Akt inhibition. The three chalcones displayed marked in vitro antitumor effects in different protocols with standard chemotherapy drugs, with acceptable toxicity on normal cells. There was no growth retrieval, after exposure to chalcone N9 alone, in a long-term assay to determine the cumulative population doubling (CPD) of human oral cancer cells. A PCR array evaluating 168 genes related to cancer and inflammation, demonstrated striking actions for N9, which altered the expression of 74 genes. Altogether, our results point out quinoxalinic chalcones, mainly N9, as potential strategies for oral cancer treatment

Intraperitoneal exposure to nano/microparticles of fullerene (C60) increases acetylcholinesterase activity and lipid peroxidation in adult zebrafish (danio rerio) brain

Even though technologies involving nano/microparticles have great potential, it is crucial to determine possible toxicity of these technological products before extensive use. Fullerenes C60 are nanomaterials with unique physicochemical and biological properties that are important for the development of many technological applications. The aim of this study was to evaluate the consequences of nonphotoexcited fullerene C60 exposure in brain acetylcholinesterase expression and activity, antioxidant responses, and oxidative damage using adult zebrafish as an animal model. None of the doses tested (7.5, 15, and 30 mg/kg) altered AChE activity, antioxidant responses, and oxidative damage when zebrafish were exposed to nonphotoexcited C60 nano/microparticles during 6 and 12 hours. However, adult zebrafish exposed to the 30 mg/kg dose for 24 hours have shown enhanced AChE activity and augmented lipid peroxidation (TBARS assays) in brain. In addition, the up-regulation of brain AChE activity was neither related to the transcriptional control (RT-qPCR analysis) nor to the direct action of nonphotoexcited C60 nano/microparticles on the protein (in vitro results) but probably involved a posttranscriptional or posttranslational modulation of this enzymatic activity. Taken together these findings provided further evidence of toxic effects on brain after C60 exposure

Extracellular superoxide dismutase is necessary to maintain renal blood flow during sepsis development

Background: Extracellular superoxide dismutase (ECSOD) protects nitric oxide (NO) bioavailability by decreasing superoxide levels and preventing peroxynitrite generation, which is important in maintaining renal blood flow and in preventing acute kidney injury. However, the profile of ECSOD expression after sepsis is not fully understood. Therefore, we intended to evaluate the content and gene expression of superoxide dismutase (SOD) isoforms in the renal artery and their relation to renal blood flow. Methods: Sepsis was induced in Wistar rats by caecal ligation and perforation. Several times after sepsis induction, renal blood flow (12, 24 and 48 h); the renal arterial content of SOD isoforms, nitrotyrosine, endothelial and inducible nitric oxide synthase (e-NOS and i-NOS), and phosphorylated vasodilator-stimulated phosphoprotein (pVASP); and SOD activity (3, 6 and 12 h) were measured. The influence of a SOD inhibitor was also evaluated. Results: An increase in ECSOD content was associated with decreased 3-nitrotyrosine levels. These events were associated with an increase in pVASP content and maintenance of renal blood flow. Moreover, previous treatment with a SOD inhibitor increased nitrotyrosine content and reduced renal blood flow. Conclusions: ECSOD appears to have a major role in decreasing peroxynitrite formation in the renal artery during the early stages of sepsis development, and its application can be important in renal blood flow control and maintenance during septic insult

Avalia??o da toxicidade induzida pela exposi??o ? microcistina-LR sobre as neurotransmiss?es colin?rgica e purin?rgica em Zebrafish (Danio rerio)

Made available in DSpace on 2015-04-14T14:51:20Z (GMT). No. of bitstreams: 1 442001.pdf: 1823261 bytes, checksum: 10761416aa58c3d7680e6ff4e42ce20f (MD5) Previous issue date: 2012-08-23Microcystins (MCs) constitute a family of cyanobacterial toxins, with more than 80 variants. These toxins are able to induce hepatotoxicity in several organisms, mainly through the inhibition of protein phosphatases PP1 and PP2A and oxidative stress generation. Recent evidence shows that MCs can either accumulate in brain or alter behavior patterns of fish species. Thus, this thesis aimed to study the effects of MC-LR (with the variable amino acids leucine (L) and arginine (R)) exposure on biochemical parameters in zebrafish, emphasizing the cholinergic and purinergic signaling, as well as to evaluate the behavioral patterns and whole-body cortisol levels. In vivo studies showed that 100 μg/L MC-LR for 24 h led to a significant increase in the AChE activity (27%) when zebrafish were exposed to the toxin dissolved in water, but did not cause any significant changes when injected intraperitoneally. In addition, semiquantitative RT-PCR analysis demonstrated that 100 μg/L MC-LR exposure also increased ache mRNA levels in zebrafish brain. The in vitro assays did not reveal any significant changes in AChE activity. We also assessed behavioral patterns and whole-body cortisol levels of adult zebrafish exposed to cell culture of the microcystin-producing cyanobacterium Microcystis aeruginosa. MC-LR exposure (100 μg/L) decreased by 63% the distance traveled and increased threefold the immobility time when compared to the control group. Interestingly, no significant alterations in the number of line crossings were found at the same MC-LR concentration and time of exposure. When animals were exposed to 50 and 100 μg/L, MC-LR promoted a significant increase (around 93%) in the time spent in the bottom portion of the tank, suggesting an anxiogenic effect. In addition, the results also showed that none of the MC-LR concentrations tested promoted significant alterations in absolute turn angle, path efficiency, social behavior, or whole-body cortisol level. Moreover, we evaluated the acute effects of different concentrations of MC-LR on NTPDases (nucleoside triphosphate diphosphohydrolases) and 5 - nucleotidase in adult zebrafish (Danio rerio) brain membranes. The results have shown no significant changes in ATP, ADP and AMP hydrolysis in zebrafish brain membranes. MC-LR in vitro also did not alter ATP, ADP and AMP hydrolysis in the concentrations tested. These findings show that acute exposure to MC-LR did not modulate ectonucleotidases activity in the tested conditions. Taken together these findings provide the first evidence that brain AChE is another potential target for MCs and that MC-LR exposure significantly impairs animal's exploratory performance. Nevertheless, further studies including long-time exposure should be performed in order to achieve a better understanding about MCLR toxicity mechanisms in the central nervous systemMicrocistinas (MCs) constituem uma fam?lia de toxinas, com mais de 80 variantes. Estas toxinas s?o capazes de induzir hepatotoxicidade em diversos organismos, principalmente atrav?s da inibi??o das fosfatases PP1 e PP2A e gera??o de estresse oxidativo. Evid?ncias recentes mostram que MCs podem acumular no c?rebro e alterar padr?es comportamentais em diferentes esp?cies de peixes. Portanto, a presente tese teve por objetivo estudar os efeitos da exposi??o ? MC-LR (com os amino?cidos vari?veis leucina (L) e arginina (R)) sobre par?metros bioqu?micos em zebrafish, enfatizando os sistemas colin?rgicos e purin?rgicos, bem como, avaliar padr?es comportamentais e n?veis de cortisol corporal. Resultados do estudo in vivo mostraram que a exposi??o a 100 μg/L de MC-LR durante 24 h causaram um aumento significativo na atividade da AChE (27%) quando zebrafish foi exposto ? toxina dissolvida em ?gua; por?m, a toxina n?o causou mudan?as significativas quando injetada intraperitonealmente. Al?m disso, a an?lise semiquantitativa de RT-PCR demonstrou que a exposi??o ? 100 μg/L de MC-LR tamb?m aumentou os n?veis de RNAm da ache em c?rebro de zebrafish. Os ensaios in vitro n?o revelaram nenhuma altera??o significativa na atividade da AChE. N?s tamb?m avaliamos padr?es comportamentais e n?veis de cortisol corporal de zebrafish adultos expostos ? cultura de c?lulas de Microcystis aeruginosa produtoras de MC-LR. A exposi??o ? MC-LR (100 μg/L) diminuiu em 63% a dist?ncia viajada e aumentou tr?s vezes o tempo de imobilidade quando comparado ao grupo controle. Interessantemente, n?o houve altera??o no n?mero de linhas cruzadas na mesma concentra??o e tempo de exposi??o ? MC-LR. Quando animais foram expostos a 50 e 100 μg/L, a MCLR promoveu um aumento significante (aproximadamente 93%) no tempo gasto na por??o inferior do aqu?rio teste, sugerindo um efeito ansiog?nico. Adicionalmente, os resultados tamb?m mostraram que nenhuma das concentra??es de MC-LR testadas promoveu altera??es significativas nas mudan?as de ?ngulo, efici?ncia de rota e intera??o social ou, no n?vel de cortisol corporal total. Al?m disso, tamb?m foi avaliado o efeito de diferentes concentra??es de MC-LR na atividade das NTPDases (nucleos?deo trifosfato difosfoidrolase) e 5 nucleotidase em membranas cerebrais de zebrafish (Danio rerio) adultos. Os resultados mostraram que n?o houve altera??o nas hidr?lises de ATP, ADP e AMP. Nos experimentos in vitro tamb?m n?o houve altera??o nas hidr?lises dos nucleot?deos nas concentra??es testadas. Estes achados mostram que exposi??o aguda ? MC-LR n?o modulou a atividade das ectonucleotidases nas condi??es testadas. Ademais, fornecem a primeira evid?ncia que a AChE cerebral ? um outro alvo potencial das MCs e que exposi??o ? MC-LR prejudica significativamente a performance explorat?ria do animal. Estudos futuros incluindo exposi??o de longo prazo dever ser feitos para um melhor entendimento dos mecanismos de toxicidade das MCs no Sistema Nervoso Centra

Associa??o entre horm?nios tireoideanos e temperamento

Made available in DSpace on 2015-04-14T14:50:54Z (GMT). No. of bitstreams: 1 410542.pdf: 194355 bytes, checksum: 1ebc57398ef39f3d171e80084726ad27 (MD5) Previous issue date: 2009-03-18Temperament is the automatic emotional and motivational bias, influencing mood, behavior and personality development. Thyroid dysfunction is more prevalent in patients with mood disorder and may interfere with treatment responsiveness, but the relationship between thyroid function and temperament has been less studied. Methods: 143 subjects (103 females) who completed the Combined Emotional and Affective Temperament Scale were evaluated for TSH, free T4 and free T3 levels. Results: There was a significantly higher proportion of cyclothymics than euthymics in the high TSH group (>4 mIU/L, p<0.05). Female volunteers with TSH<4 mIU/L had significantly higher scores for anxious and lower scores for irritable temperaments. Among volunteers with TSH<4 mIU/L, there was a positive correlation of free T4 with apathetic temperament score (r=0.23, p<0.01). This correlation persisted in males (r=0.33, p=0.037) and females (r=0.22, p=0=0.026) and if only volunteers with no medication at all were included (r=0.23, p=0.015, n=108). Conclusion: Thyroid hormones seem to be associated with temperament in a non-linear way. Findings in patients with mood disorders and subclinical hypothyroidism cannot be generalized to understand the physiological role of thyroid hormones on emotion and affect.O temperamento ? o vi?s autom?tico no terreno das emo??es e da motiva??o, influenciando humor, comportamento e o desenvolvimento da personalidade. A disfun??o da tireoide ? mais prevalente em pacientes com transtorno de humor e pode interferir na resposta ao tratamento. No entanto, a rela??o entre a fun??o da tireoide e o temperamento tem sido pouco estudada. M?todos: 143 sujeitos (103 mulheres) preencheram a Escala de Temperamento Afetivo e Emocional (ETAFE) e foram avaliados os n?veis s?ricos de TSH, T4 livre e T3 livre. Resultados: Houve uma propor??o significativamente maior de ciclot?micos do que eut?micos no grupo com TSH elevado (>4 mIU/L, p<0.05). Mulheres com TSH<4 mIU/L tiveram escores significativamente maiores de temperamento ansioso e menores de temperamento irrit?vel. Entre volunt?rios com TSH<4 mIU/L, houve uma correla??o positiva de T4 livre com escores de temperamento ap?tico (r=0.23, p<0.01). Esta correla??o persistiu em homens (r=0.33, p=0.037) e em mulheres (r=0.22, p=0=0.026) e na an?lise incluindo somente volunt?rios sem qualquer medica??o (r=0.23, p=0.015, n=108). Conclus?o: Os horm?nios tireoideanos parecem estar associados com o temperamento de modo n?o linear. Achados em pacientes com transtornos de humor e hipotireoidismo subcl?nico n?o podem ser generalizados para o entendimento do papel fisiol?gico dos horm?nios tireoideanos nos temperamentos afetivos e emocionai