Envolvimento dos sistemas purin?rgico, colin?rgico e dopamin?rgico na neurotoxicidade induzida por metais e agrot?xicos em peixe-zebra (Danio rerio)

Submitted by Caroline Xavier ([email protected]) on 2017-06-30T18:09:29Z No. of bitstreams: 1 TES_STEFANI_ALTENHOFEN_PARCIAL.pdf: 820184 bytes, checksum: 93540eb7fece868ec872a31e8f894852 (MD5)Approved for entry into archive by Caroline Xavier ([email protected]) on 2017-06-30T18:09:36Z (GMT) No. of bitstreams: 1 TES_STEFANI_ALTENHOFEN_PARCIAL.pdf: 820184 bytes, checksum: 93540eb7fece868ec872a31e8f894852 (MD5)Made available in DSpace on 2017-06-30T18:09:44Z (GMT). No. of bitstreams: 1 TES_STEFANI_ALTENHOFEN_PARCIAL.pdf: 820184 bytes, checksum: 93540eb7fece868ec872a31e8f894852 (MD5) Previous issue date: 2017-03-06Neurotoxic agents, such as pesticides, organic solvents and metals, are capable to alter normal CNS activity. Manganese (Mn) is a metal found in the environment, which when in excess, accumulates in the CNS making it a potential hazard to health. In addition to Mn, other neurotoxic agents can cause changes, leading to deficits in neurotransmission systems. The growth of crop pests has exponentially increased the use of agrochemicals to maintain plantations. The fungicide tebuconazole is a triazole used in crops, such as barley, wheat, peanuts and orchard fruits and related to behavioral and oxidative changes. The insecticide dichlorvos, belongs to organophosphate family, acts through the acetylcholinesterase (AChE) inhibition, leading to hyperstimulation of cholinergic receptors. Cholinergic system is characterized by the action of acetylcholine (ACh) on muscarinic and nicotinic receptors. The level of this molecule is regulated by acetylcholinesterase (AChE), which catalyzes degradation of ACh into choline and acetate. Purinergic system is characterized by the action of ATP and adenosine on purinoreceptor P2 and P1, respectively. The levels of these molecules are regulated by ectonucleotidases, which constitute the extracellular cascade for ATP hydrolysis to adenosine. Adenosine can be subsequently deaminated to inosine by action of adenosine deaminase (ADA). Dopamine (DA), synthesized from L-DOPA, is the neurotransmitter of the dopaminergic system and it acts through its D1-D5 receptors, controlling the start and execution of movement. This study aims to evaluate the effects of exposure to manganese and pesticides, such as dichlorvos and tebuconazole, on behavioral parameters in larval and adult zebrafish, as well as its effects on purinergic, cholinergic and dopaminergic signaling. Exposure to MnCl2 in the early stages of development (1 hpf - 5 dpf) was able to reduce the distance traveled, absolute turn angle and mobile time of the larvae at 5, 7 and 10 dpf. In addition, it caused an increase in TH levels at 5 and 7 dpf, followed by a reduction at 10 dpf. There was also an increase in markers of cell death. In adult animals, exposure during 96 hours caused a reduction in distance traveled, number of line crossings and absolute turn angle, and an inhibition on memory acquisition through the inhibitory avoidance task. In addition, adult animals exposed to MnCl2 showed increased levels of markers of cell death, TH and DOPAC (3,4-dihydroxyphenylacetic acid) in the brain. The 96-hour exposure to this metal was also able to inhibit the NTPDases and ecto-ADA activities and to reduce ADA2.1-mRNA transcripts, besides for increasing ADP levels and reducing the amount of AMP, ADO and INO in the incubation medium. Tebuconazole was able to increase the ocular distance of larvae at 5 dpf and reduce the exploratory behavior of these animals, and still decrease the locomotor activity of 96 hours exposed adult zebrafish. Moreover, this fungicide decreased AChE activity in both 5 dpf larvae and brains of adult animals. Exposure to dichlorvos (1 hpf - 7 dpf) reduced body length, heartbeat rate and larval surface at 7 dpf as well as affected the escape capacity of larvae at 7 and 14 dpf. Further, it reduced exploratory behavior at 7 and 14 dpf, maintaining this pattern when animals became young adults at 30 dpf, and adults at 70 dpf. However, the analysis performed at 120 dpf showed a recovery of behavioral activity equal to the control. In addition, the analysis of exposure to dichlorvos in the early stages of development at 120 dpf on the enzymes of the purinergic system, showed that this insecticide is able to elevate the ecto-5'-nucleotidase activity and reduce the ecto-ADA activity. The results showed that neurotoxic agents, such as Mn, dichlorvos and tebuconazole, play a role in the larval and adult behavior of zebrafish, and affect different neurotransmission systems. Such behavioral changes may be associated with the deficits observed in neurochemical and molecular mechanisms investigated.Agentes neurot?xicos, tais como pesticidas, solventes org?nicos e metais, s?o capazes de alterar a atividade normal do Sistema Nervoso Central (SNC). O mangan?s (Mn) ? um metal encontrado no ambiente que, quando em excesso, acumula-se no SNC, tornando-se um perigo potencial para a sa?de. Al?m do Mn, outros agentes neurot?xicos podem causar altera??es, levando a d?ficits em sistemas de neurotransmiss?o. O crescimento de pragas de lavoura tem aumentado exponencialmente o uso de agrot?xicos para manuten??o de planta??es. O fungicida tebuconazol ? um triazol utilizado em culturas como a cevada, trigo, amendoim e frutas do pomar e relacionado com altera??es comportamentais e oxidativas. O inseticida dicl?rvos, pertence a fam?lia dos organofosforados atuando atrav?s da inibi??o da acetilcolinesterase (AChE), que leva ? hiperestimula??o dos receptores colin?rgicos. O sistema colin?rgico ? caracterizado pela a??o da acetilcolina (ACh) nos receptores muscar?nicos e nicot?nicos. O n?vel dessa mol?cula ? regulado pela acetilcolinesterase (AChE), que catalisa a degrada??o da ACh em colina e acetato. O sistema purin?rgico ? caracterizado pela a??o do ATP e adenosina (ADO) nos purinoreceptores P2 e P1, respectivamente. Os n?veis dessas mol?culas s?o regulados pela a??o das ectonucleotidases que catalisam a hidr?lise do ATP a adenosina (ADO). A ADO pode ser desaminada a inosina (INO) pela a??o da adenosina desaminase (ADA). A dopamina (DA), sintetizada a partir da L-DOPA, ? o neurotransmissor do sistema dopamin?rgico e age atrav?s dos seus receptores D1-D5, controlando o in?cio e execu??o do movimento. Portanto, este estudo visa avaliar os efeitos da exposi??o ao mangan?s e agrot?xicos, tais como dicl?rvos e tebuconazol, sobre par?metros comportamentais em peixe-zebra nos est?gios larval e adulto, bem como os seus efeitos sobre a sinaliza??o purin?rgica, colin?rgica e dopamin?rgica. A exposi??o ao MnCl2 nos est?gios iniciais de desenvolvimento (1 hpf - 5 dpf) foi capaz de reduzir a dist?ncia percorrida, o ?ngulo de giro absoluto e o tempo de mobilidade das larvas aos 5, 7 e 10 dpf. Al?m disso, causou um aumento nos n?veis de TH aos 5 e 7 dpf, seguido por uma redu??o em 10 dpf. Tamb?m foi observado um aumento dos marcadores de morte celular. Em animais adultos, a exposi??o ao longo de 96 horas causou redu??o na dist?ncia percorrida, n?mero de cruzamentos e ?ngulo de giro absoluto, e ainda uma redu??o na aquisi??o de mem?ria atrav?s da tarefa de esquiva inibit?ria. Al?m disso, os animais adultos expostos a MnCl2 apresentaram aumento nos n?veis de marcadores de morte celular, al?m de TH e DOPAC (?cido 3,4-di-hidroxifenilac?tico) no enc?falo. A exposi??o por 96 horas a este metal tamb?m foi capaz de inibir a atividade das NTPDases e da ecto-ADA e reduzir os transcritos de RNAm do gene ADA2.1, al?m de aumentar os n?veis de ADP e reduzir a quantidade de AMP, ADO e INO no meio. O tebuconazol foi capaz de aumentar a dist?ncia ocular de larvas aos 5 dpf e reduzir a capacidade explorat?ria desses animais, e ainda diminuir a atividade locomotora de peixe-zebra adultos expostos por 96 horas. Al?m disso, este fungicida diminuiu a atividade da AChE tanto em larvas de 5 dpf, quanto em enc?falo de animais adultos. Al?m do mais, o tebuconacol aumentou a express?o relativa de mRNA da AChE em larvas, no entanto, n?o alterou em adultos. A exposi??o ao dicl?rvos, nas fases iniciais do desenvolvimento (1 hpf - 7 dpf), reduziu o tamanho corporal, a taxa de batimentos card?acos e a superf?cie dos olhos de larvas de 7 dpf, bem como afetou a capacidade de escape de larvas aos 7 e 14 dpf. Al?m disso, reduziu a capacidade explorat?ria aos 7 e 14 dpf, padr?o mantido quando os animais tornaram-se adultos jovens aos 30 dpf, e adultos aos 70 dpf. No entanto, as an?lises realizadas aos 120 dpf mostraram recupera??o da atividade comportamental similar ao grupo controle. A an?lise aos 120 dpf da exposi??o ao dicl?rvos nas fases iniciais do desenvolvimento sobre as enzimas do sistema purin?rgico mostrou que este inseticida ? capaz de elevar a atividade da ecto-5?-nucleotidase e reduzir a atividade da ecto-ADA. Os resultados mostram que os agentes neurot?xicos, tais como Mn, dicl?rvos e tebuconazol t?m atua??o significativa sobre o comportamento do peixe-zebra em est?gio larval e adulto, al?m de afetar diferentes sistemas de neurotransmiss?o. Tais altera??es comportamentais podem estar associadas aos d?ficits observados nos mecanismos neuroqu?micos e moleculares investigados

Avalia??o dos efeitos de f?rmacos benzodiazep?nicos sobre o catabolismo de nucleot?deos, nucleos?deos e acetilcolina em enc?falo de zebrafish adulto : (Danio rerio)

Made available in DSpace on 2015-04-14T14:51:23Z (GMT). No. of bitstreams: 1 447376.pdf: 1656350 bytes, checksum: c0a2b1db197a97d3100dfa1ffa101f1f (MD5) Previous issue date: 2012-12-26Benzodiazepines, such as diazepam and midazolam, are a widely used class of drugs for anxiety treatment, with anxiolytic, hypnotic, and anticonvulsant properties. The use of zebrafish (Danio rerio) as a model for evaluating pharmacological mechanisms has gained importance due to their rapid development and high sensitivity to drugs. Studies have shown that behavioral parameters were altered in zebrafish after benzodiazepine treatment. Many neurotransmitter systems have been identified in this species, including purinergic and cholinergic system. Purinergic system is characterized by the action of ATP and adenosine on purinoreceptor P2 and P1, respectively. The levels of these molecules are regulated by ectonucleotidases, especially nucleoside triphosphate diphosphohydrolase (NTPDases) and ecto-5'-nucleotidase, which constitute the extracellular cascade for ATP hydrolysis to adenosine. Adenosine can be subsequently deaminated to inosine by action of adenosine deaminase (ADA). ATP is coreleased with other neurotransmitters, including acetylcholine, and has been demonstrated that adenosine can control the release of acetylcholine. Cholinergic system is characterized by the action of acetylcholine (ACh) on muscarinic and nicotinic receptors. The level of this molecule is regulated by acetylcholinesterase (AChE), which catalyzes degradation of ACh into choline and acetate. Since there are few reports relating these enzyme activities and the action mechanism of benzodiazepines, the aim of this study was evaluated the in vitro and ex vivo effects of classical benzodiazepines, such as diazepam and midazolam, on NTPDase, ecto-5'nucleotidase, ADA, and AChE activities in zebrafish brain and gene expression pattern in treatments that induced changes in enzyme activity in the ex vivo experiments. In order to elucidate whether diazepam or midazolam has direct effects on these enzymes, we performed in vitro experiments. Diazepam, at 500 μM, promoted a decrease on ATP hydrolysis (66%), whereas this drug, at 10-500 μM, reduced ADP hydrolysis (40-54%, respectively). Midazolam also decreased ATP (16-71% for 10-500 μM, respectively) and ADP hydrolysis (48-73% for 250-500 μM, respectively), and ecto-ADA activity (26-27.5% for 10-500 μM, respectively). Diazepam and midazolam did not induce significant changes on ecto-5?-nucleotidase activity at the concentrations tested. Concerning to AChE activity, 500 μM diazepam promoted a decrease on ACh hydrolysis (19%), whereas midazolam, at 50-500 μM, reduced AChE activity (18-79%, respectively). For ex vivo experiments, diazepam or midazolam exposures did not alter NTPDase activities in zebrafish brain membranes. AMP hydrolysis was decreased in animals treated with of 0.5 and 1mg/L midazolam (31.5% and 36.1%, respectively) when compared to the control group. However, diazepam was unable to alter ecto-5 -nucleotidase. Both drugs significantly decreased the ecto-ADA activity, whereas diazepam and midazolam reduced the adenosine hydrolysis at a concentration of 1.25 mg/L (30.85%) and 1 mg/L (32.8%), respectively. Diazepam did not alter cytosolic-ADA activity; however, the exposure to 0.1 mg/L midazolam induced a significant increase in cytosolic-ADA (39.9%) when compared with the control group. The gene expression pattern demonstrated that the CD73 transcript levels were increased (41.7%) after treatment with 0.5 mg/L midazolam. Moreover, the changes caused by diazepam and midazolam in the ADA activity are not related to the transcriptional control. Concerning the cholinerg signaling, diazepam decreased ACh hydrolysis at 1.25 mg/L (30.7%) when compared to the control group. Similarly, the exposure to 0.5 mg/L midazolam also changed the enzymatic activity of AChE promoting an increase in the ACh hydrolysis (36.7%). It is possible to suggest that these drugs can induce a direct effect on the enzyme activities, since we observed a decreased on nucleotide and nucleoside hydrolysis after in vitro exposure. In addition, the alteration on AMP hydrolysis, ADA and AChE activities suggest a modulation of extracellular adenosine and ACh levels induced by benzodiazepine exposure.F?rmacos benzodiazep?nicos, como diazepam e midazolam, s?o muito usados na pr?tica cl?nica para o tratamento da ansiedade, possuindo propriedades ansiol?ticas, hipn?ticas e anticonvulsivantes. O uso do zebrafish (Danio rerio) como modelo para avaliar mecanismos farmacol?gicos tem ganhado grande import?ncia devido ao r?pido desenvolvimento e alta sensibilidade a drogas que essa esp?cie possui. Estudos t?m demonstrado que par?metros comportamentais mostraram-se alterados em zebrafish ap?s tratamento com benzodiazep?nicos. Muitos sistemas de neurotransmiss?o foram identificados nessa esp?cie, incluindo os sistemas purin?rgico e colin?rgico. O sistema purin?rgico ? caracterizado pela a??o do ATP e adenosina (ADO) nos purinoreceptores P2 e P1, respectivamente. Os n?veis dessas mol?culas s?o regulados pela a??o das ectonucleotidases, especialmente as nucleos?deo trifosfato difosfoidrolases (NTPDases) e a ecto-5 -nucleotidase, que catalisam a hidr?lise do ATP a adenosina. A adenosina pode ser desaminada a inosina pela a??o da adenosina desaminase (ADA). O ATP ? coliberado com outros neurotransmissores, entre eles a acetilcolina, e tem sido demonstrado que a adenosina pode controlar a libera??o de acetilcolina. O sistema colin?rgico ? caracterizado pela a??o da acetilcolina (ACh) nos receptores muscar?nicos e nicot?nicos. O n?vel dessa mol?cula ? regulado pela acetilcolinesterase (AChE), que catalisa a degrada??o da ACh em colina e acetato. Uma vez que existem poucos relatos relacionando esses sistemas enzim?ticos e a a??o de f?rmacos benzodiazep?nicos, o objetivo deste estudo foi avaliar o efeito in vitro e ex vivo do tratamento com f?rmacos benzodiazep?nicos, tais como diazepam e midazolam, sobre a atividade das NTPDases, ecto-5'-nucleotidase, ADA and AChE no enc?falo de zebrafish e o padr?o de express?o g?nica nos tratamentos que induziram altera??es na atividade enzim?tica nos experimentos ex vivo. A fim de elucidar se o diazepam e o midazolam t?m efeitos diretos nessas enzimas, experimentos in vitro foram realizados. Na concentra??o de 500 μM, o diazepam diminuiu a hidr?lise de ATP (66%) e, nas concentra??es de 10-500 μM, este f?rmaco reduziu a hidr?lise de ADP (40-54%, respectivamente). O midazolam tamb?m diminuiu a hidr?lise do ATP (16-71% para 10-500 μM, respectivamente), ADP (48-73% para 250-500 μM, respectivamente) e a atividade da ecto-ADA (26-27,5% para 10-500 μM, respectivamente). Diazepam e midazolam n?o induziram altera??es significativas sobre a atividade da ecto-5?-nucleotidase nas concentra??es testadas. Com rela??o ? atividade da AChE, o diazepam, 500 μM, promoveu uma diminui??o na hidr?lise de ACh (19%) e o midazolam, nas concentra??es de 50-500 μM, reduziu a atividade da AChE (18-79%, respectivamente). Nos experimentos ex vivo, as exposi??es ao diazepam e midazolam n?o alteraram a atividade enzim?tica das NTPDases em membranas cerebrais de zebrafish. A hidr?lise do AMP diminuiu em animais tratados com 0.5 mg/L e 1 mg/L de midazolam (31.5% e 36.1%, respectivamente) quando comparados com o grupo controle. Entretanto, o diazepam foi incapaz de alterar a atividade da ecto-5 -nucleotidase. Ambos os f?rmacos diminu?ram significativamente a atividade da ecto-ADA, sendo que o diazepam e o midazolam reduziram a hidr?lise da adenosina na concentra??o de 1.25 mg/L (30.85%) e 1 mg/L (32.8%), respectivamente. O diazepam n?o alterou a atividade da ADA citos?lica, no entanto a exposi??o a 0.1 mg/L de midazolam induziu um significativo aumento na atividade dessa enzima (39.9%) quando comparado ao grupo controle. O padr?o de express?o g?nica demonstrou que os n?veis de transcritos do CD73 apresentaram-se reduzidos (41,7%) ap?s o tratamento com 0.5 mg/L de midazolam. Com rela??o a sinaliza??o colin?rgica, diazepam diminuiu a hidr?lise da ACh na concentra??o de 1.25 mg/L (30.7%) quando comparado ao grupo controle. Similarmente, a exposi??o ? concentra??o de 0.5 mg/L de midazolam tamb?m alterou a atividade enzim?tica da AChE, promovendo um aumento na hidr?lise da ACh (36.7%). ? poss?vel sugerir que essas drogas podem induzir um efeito direto na atividade enzim?tica, uma vez que foi observada uma diminui??o na hidr?lise de nucleot?deos e nucleos?deos ap?s a exposi??o in vitro. Al?m disso, as altera??es na hidr?lise do AMP e atividade da ADA e da AChE sugerem uma modula??o dos n?veis extracelulares de adenosina e acetilcolina induzidos pela exposi??o aos f?rmacos benzodiazep?nicos

Intraventricular Aβ injection significantly impairs avoidance of an aversive stimulus.

<p>5dpf larvae escape behavior from an aversive stimulus (charts were plotted with means and SD escape responses to a non-stimuli area). Two-way ANOVA followed by Bonferroni demonstrated a significant effect of treatment factor (H₂O and LiCl) (p<0.0001; F_(1,166) = 40.77; N = 10 in triplicates). Aβ injected animals showed diminished escape responses when compared to their vehicle control group in H₂O and LiCl-treated groups (* indicates p<0.05 for both comparisons). LiCl treatment increased escape responses in all groups when compared to their respective H₂O-treated equivalent (a indicates p<0.05 for noninjected Ø groups; p<0.0001 for veh-injected groups and p<0.001 for Aβ-injected groups in Student-t test.</p

Intraventricular injection alters apoptotic targets.

<p>A, representative Western blots showing immunoreactivity of indicated proteins normalized to β-actin. B, Western blots quantification of absorbance (charts were plotted with means and SD). Two-way ANOVA followed by Bonferroni posttest didn’t show significant differences (p = 0.1153, F_(2,41) = 2.28 for p53; p = 0.3063, F_(2,48) = 1.21 for bax; p = 0.4420, F_(2,45) = 0.83 for caspase-8; N = 3 in triplicates) in Aβ injected animals compared to their vehicle control group in H₂O or LiCl-treated groups. P53 and caspase-8 levels differed between H₂O-veh and H₂O_–Aβ and noninjected H₂O_–Ø controls (*p<0.05, **p<0.01). Among noninjected animals, LiCl treatment increased p53 and caspase-8 protein levels compared to their respective H₂O-treated equivalent (a indicates p<0.01 for caspase-8 and p<0.0001 for p53 in Student-t test). C, q-PCR analysis normalized to three constitutive genes (b-actin, rpl13a and ef1a) (charts were plotted with means and SD). Two-way ANOVA followed by Bonferroni posttest didn’t show significant differences on gene expression (p = 0.5473, F_(2,88) = 0.61 for p53; p = 0.7313, F_(2,48) = 0.31 for bax; p = 0.8822, F_(2,50) = 0.13 for bcl-2; N = 6 in duplicates).</p

Brain Intraventricular Injection of Amyloid-β in Zebrafish Embryo Impairs Cognition and Increases Tau Phosphorylation, Effects Reversed by Lithium - Figure 3

<p>Intraventricular Aβ injection increases tau-p at Ser202 and Thr205 residues and this effect is reversed by lithium treatment. Representative Western blots showing immunoreactivity to phosphorylated tau protein normalized to β-actin and quantification of absorbance (charts were plotted with means and SD). Two-way ANOVA followed by Bonferroni demonstrated a significant effect of treatment factor (p<0.0001, F_(1,42) = 296.02; N = 3 in triplicates). H₂O_–Aβ injected animals showed increased levels of tau phosphorylation in relation to H₂O-veh (*p<0.001). LiCl treatment decreased tau-p in all groups when compared to their respective H₂O-treated equivalent (a indicates p<0.0001 in Student-t test for all comparisons).</p