Acronym NEUTOXMER
Category
Fisheries
Title Neurotoxicity of mercury in fish and association with morpho-functional changes in the brain and behavioral deviations Programme National Programme
Instrument (FP6)
Contact Type (FP7)
Strand (Interreg)
NA
Theme (FP7)
Activity Area (FP6)
Regional Area (Interreg)
Action (COST)
NA
Specific Programme (FP7)
NA
Funding source National Coordinator Mário Pacheco Coordinator email NA
Coordinator institution
CESAM - Centre for Environmental and Marine Studies (Portugal)
Institutions involved
INRB - National Institute of Biological Resources, IP (Portugal) ,
UMinho - University of Minho (Portugal) ,
Start year 2013 End year 2015 Funding (€) € 125,280 Website https://www.cesam-la.pt/projetos/neutoxmer-neurotoxicidade-do-mercurio-em-peixes-e-associacao-com-alteracoes-morfo-funcionais-no-cerebro-e-desvios-comportamentais/ Summary "Neurotoxicity is one of the most harmful effects of xenobiotics. In this context, mercury (Hg) compounds, including methylmercury (MeHg), have been of major concern, particularly in the field of human health. The hazardousness, persistence and ubiquity of Hg in natural waters are well known. However, the evaluation of its potential to induce neuronal dysfunction in aquatic animals is a subject that has been little explored. Thus, the leitmotif of the project was the recognition of a gap in the knowledge about the neurotoxicity of Hg in fish, and in particular in the identification of its mechanisms and repercussions on brain functioning and possible behavioral changes. Fish are highly susceptible to environmental exposure to Hg, which, combined with its ecological relevance, reinforces the relevance of this study. High levels of Hg have been detected in the brains of fish, and this was the organ that best reflected environmental levels. The well-documented neurotoxicity in humans and rodents, coupled with the strong indications provided in the same direction by the few studies in fish points to the need for a scientific effort in this direction.
Although Hg has been implicated in neurodegeneration, the underlying mechanisms remain unclear, especially in fish. In this context, research into the involvement of oxidative stress is particularly relevant, given that the neurotoxicity of Hg in mammals has been associated with the production of reactive oxygen species (ROS). Compared to other organs, the brain is particularly vulnerable given its potential for ROS production.
Thus, the main questions to be investigated are: (1) to clarify which species of Hg (inorganic vs. MeHg) preferentially accumulates in the brain and the contribution of the different absorption pathways (water vs. diet); (2) research the role of oxidative stress in Hg neurotoxicity; (3) investigate morpho-functional changes in the brain; (4) clarify whether environmentally relevant Hg levels induce behavioral changes. Cause-effect relationships between point 1 and points 2, 3, 4 will also be investigated, as well as mechanistic associations between points 2, 3 and 4. In addition, (5) the reversibility of previous effects in a post-exposure period will be assessed in parallel with the evolution of accumulated Hg levels in the brain.
Considering the central issues of the project, an integrated approach was planned, involving laboratory experiments with exposure and post-exposure periods. Exposures will be carried out via water (inorganic Hg) and via food (inorganic and MeHg) separately and in combination. As an innovative strategy to promote knowledge of the toxicokinetics and toxicodynamics of Hg, and particularly to clarify how inorganic Hg reaches the brain, the metal made available via water will be isotopically labeled (201HgCl). Subsequently, the levels of inorganic Hg, 201Hg and MeHg in the blood, specific areas of the brain and spinal cord will be quantified.
The influence of temperature (simulating contrasting seasons, i.e. winter/summer) on the absorption and fate of the different forms of the metal in the fish body, as well as on the biochemical responses and morpho-functional changes of the brain, will be taken into account.
Among the parameters to be determined in the brain are the activity of acetylcholinestrase, as well as a battery of oxidative stress parameters (enzymatic and non-enzymatic antioxidants, total antioxidant capacity and oxidative damage in lipids and proteins). In the evaluation of morpho-functional alterations, histopathological and histochemical parameters, the expression of neurotransmitter receptors, as well as levels of apoptosis and neurogenesis of the limbic system will be used. Considering that behavioural disorders are an integrated manifestation of biochemical, structural and functional changes, the fish will be monitored for locomotor and feeding activity.
The teleost Diplodus sargus will be adopted as a test organism as it meets most of the requirements of a bioindicator species.
The project is an innovative research that will contribute to the elucidation of Hg neurotoxicity in fish. The proposed strategy is completely new in the context of ecotoxicology, given its integrative character, embodied by the wide spectrum of effects to be assessed. The expected results will provide useful recommendations for decision-makers in the (re)formulation of environmental protection regulations."
Keywords
Seabream;
Toxic substances;
Impacts;
Fish biology;
Fish;
Marine Region
0
NA
Marine Region Map
