of environmental exposures on adrenal function - ecophysiology and ecotoxicology
Field studies and standardized stress challenges in vivo, or in
vitro using ACTH/dbcAMP with head kidney fragments, test the functional
integrity of the hypothalamo-pituitary-adrenal/interrenal axis in wild
species exposed to pollutants in the aquatic ecosystems. A suite of Biomarkers
of exposure and effects are also measured to characterize the physiological
status of the organisms (growth, reproductive status, metabolism, morphology
of vital organs). These findings, together with data on exposure, are
important for Ecological Risk Assessment (ERA) in fish and amphibians
exposed to pollutants in the wild.
Gravel A. et al. 2005;
Levesque H. et al. 2003;
Campbell et al. 2003;
Dorval et al. 2005; Levesque
H. et al. 2002; Sherwood
G. et al. 2000; Laflamme
J.S. et al. 2000.
of action of adrenotoxicants in adrenal steroidogenic cells of teleosts
The effects and mechanisms of toxicity of pollutants (pesticides, metals,
pharmaceuticals) are investigated in vitro in adrenal cells of
teleost fish. These studies aim to identify the intracellular sites of
action of adrenotoxicants, determine the concentrations that are lethal
to cells (LC50) and the effective concentrations that disrupt hormone
synthesis (EC50), and provide quantitative data to compare endocrine toxicity
of environmentally relevant pollutants.
Gagnon et al.
2006; Bisson M.&
Hontela A. 2002; Leblond
V.S. et al. 2001; Benguira
S.& Hontela A. 2000.
stress as a mechanism of adrenotoxicity
The role of oxidative stress in adrenotoxicity of model toxicants (e.g.
endosulfan, selenium) is investigated both in vitro in fish head kidney
cells and also in vivo in whole animals by measuring activities of enzymes
that modulate the oxidative status of cells (glutathione peroxidase, catalase),
antioxidants (GSH) and lipid peroxidation. Our studies provided new knowledge
about the vulnerability to oxidative stress of the secretory pathways
leading to cortisol synthesis.
Dorval J.& Hontela
A. 2003; Dorval et
al. 2003; Miller et
calcium homeostasis as a target of adrenotoxicants
The interactions of calcium and specific adrenotoxicants (e.g. cadmium,
endosulfan) are investigated in vitro using a pharmacological approach
with agonists and antagonists of calcium channels in isolated head kidney
A. 2006; Raynal
et al. 2005; Gagnon
et al. 2007; Hontela et al. 2007.
Endocrine Toxicology and extrapolation between species
Physiological mechanisms underlying the important differences in vulnerability
of different animal species to pollutants are investigated in the laboratory
and in the field using in vivo and in vitro approaches.
These data are important for toxicological assessments and extrapolation
Goulet B.& Hontela
A. 2003; Lacroix
A.& Hontela A. 2004; Raynal et al. 2005.
Lana Miller, PhD
Andrea Dann, MSc
Heather Bird, technician
MAIN PAGE |