| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 1.94 MB | Adobe PDF |
Authors
Abstract(s)
A obesidade é um problema crescente dos tempos atuais, com incidência tanto em países
desenvolvidos como em países em desenvolvimento. É considerada uma epidemia pela
Organização Mundial de Saúde (OMS) e tem suscitado o interesse da comunidade científica. As
explicações clássicas para a obesidade são a ingestão excessiva de calorias, a falta de
exercício físico e os fatores genéticos. No entanto estas explicações não conseguem
esclarecer completamente a epidemia da obesidade. No ano de 2006, surgiu um novo factor
explicativo associado à exposição a um conjunto de contaminantes ambientais, os
denominados obesogénios.
A Daphnia magna é um organismo invertebrado, reconhecido pelas agências reguladoras como
um organismo modelo para testes toxicológicos. No entanto, o seu uso no estudo de
patologias humanas ainda é limitado. De entre todas as vantagens associadas ao uso deste
organismo neste contexto, talvez a principal se prenda com o facto de este crustáceo possuir
uma homologia de 94% com os genes humanos (a melhor de todos os invertebrados, incluindo
modelos clássicos como, por exemplo, Drosophila melanogaster). Esta característica
associada ao facto de se tratar de um organismo de fácil manutenção em laboratório, ter um
ciclo de vida curto, ser pequeno e transparente, e ser possível o estudo da acumulação
lipídica de uma forma simples, tornam-no num modelo promissor para o estudo da ação dos
compostos obesogénicos.
Assim, o objetivo desta dissertação é perceber o efeito da exposição a potenciais obesogénios
presentes em produtos usados quotidianamente, tais como a bijutaria, e avaliar a sua
potencial toxicidade e obesogenicidade. Foram realizados testes agudos e crónicos com o
objetivo de perceber o efeito da exposição a nível da reprodução, do crescimento e da
quantidade de lípidos acumulados. Para efeitos comparativos, foi ainda realizado um teste
agudo com o obesogénio de referência, o tributilestanho (TBT).
Os resultados obtidos fornecem pela primeira vez evidências científicas que a exposição
aguda e crónica à bijuteria aumenta a quantidade de lípidos e a exposição crónica afeta o
crescimento, reprodução e tem efeitos letais nas Daphnias expostas.
Com o intuito de perceber quais os elementos presentes na bijutaria com potencial
obesogénico e tóxico foram quantificados os níveis de metais presentes em solução. De entre
os metais não essenciais, a prata e o cádmio foram aqueles que registaram níveis mais
elevados.
Os resultados obtidos sugerem uma elevada toxicidade e potencial obesogénico da bijutaria
analisada, reforçando a necessidade de avaliação de risco associado à exposição a produtos
de uso quotidiano.
Obesity is an emerging and global problem affecting both developed and developing countries. It is considered an epidemic by the World Health Organization (WHO) and the scientific community made it a topic of increasing interest. Traditional explanations for obesity include excessive calorie intake, lack of exercise and genetic factors. However, these explanations cannot fully elucidate the obesity epidemic. In 2006, a new explanation emerged, and obesity was associated with exposure to a set of environmental contaminants, the so-called obesogens. Daphnia magna is an invertebrate organism, acknowledged by regulatory agencies as a model organism for toxicological tests. However, its use on the study of human pathologies is still limited. Aside from all the advantages associated with this organism, perhaps the most important characteristic is that this crustacean possesses a 94% homology with human genes (the highest amog invertebrates, even higher than classical models such as, for instance, Drosophila melanogaster). This characteristic associated with is the easiness of laboratory maintaenance, short life cycle, small and transparent body, and allowing for the study of lipid accumulation in a direct manner, renders D. magna as a promising model for the study of the action of obesogens. Thus, the objective of this dissertation is to study the effects of exposure to potential obesogens present in consumer products, such as jewelry, and to evaluate its potential toxicity and obesogenicity. Acute and chronic tests were performed in order to evaluate the effect of exposure on reproduction, growth and the amount of accumulated lipids. For comparative purposes, an acute test was also performed with the model obesogen, tributyltin (TBT). The results obtained provide, for the first time, scientific evidence that acute and chronic exposure to jewelry increases the amount of lipids, and that chronic exposure affects growth, reproduction and have lethal effects on the exposed Daphnids. In order to understand which elements present in the jewelry have obesogenic and toxic potential, the levels of metals in solutions obtained after jewelry extractions were quantified. Among non-essential metals, silver and cadmium were those that recorded the highest levels. The results obtained suggest high toxicity and obesogenic potential for the jewelry used in the assays, reinforcing the need for risk assessment associated with exposure to consumer products.
Obesity is an emerging and global problem affecting both developed and developing countries. It is considered an epidemic by the World Health Organization (WHO) and the scientific community made it a topic of increasing interest. Traditional explanations for obesity include excessive calorie intake, lack of exercise and genetic factors. However, these explanations cannot fully elucidate the obesity epidemic. In 2006, a new explanation emerged, and obesity was associated with exposure to a set of environmental contaminants, the so-called obesogens. Daphnia magna is an invertebrate organism, acknowledged by regulatory agencies as a model organism for toxicological tests. However, its use on the study of human pathologies is still limited. Aside from all the advantages associated with this organism, perhaps the most important characteristic is that this crustacean possesses a 94% homology with human genes (the highest amog invertebrates, even higher than classical models such as, for instance, Drosophila melanogaster). This characteristic associated with is the easiness of laboratory maintaenance, short life cycle, small and transparent body, and allowing for the study of lipid accumulation in a direct manner, renders D. magna as a promising model for the study of the action of obesogens. Thus, the objective of this dissertation is to study the effects of exposure to potential obesogens present in consumer products, such as jewelry, and to evaluate its potential toxicity and obesogenicity. Acute and chronic tests were performed in order to evaluate the effect of exposure on reproduction, growth and the amount of accumulated lipids. For comparative purposes, an acute test was also performed with the model obesogen, tributyltin (TBT). The results obtained provide, for the first time, scientific evidence that acute and chronic exposure to jewelry increases the amount of lipids, and that chronic exposure affects growth, reproduction and have lethal effects on the exposed Daphnids. In order to understand which elements present in the jewelry have obesogenic and toxic potential, the levels of metals in solutions obtained after jewelry extractions were quantified. Among non-essential metals, silver and cadmium were those that recorded the highest levels. The results obtained suggest high toxicity and obesogenic potential for the jewelry used in the assays, reinforcing the need for risk assessment associated with exposure to consumer products.
Description
Keywords
Compostos Obesogénicos Daphnia Magna Obesidade Tributilestanho