RESEARCH TOPICS

1. Impact 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.

2. Mechanisms 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.

3. Oxidative 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 al. 2007.

4. Intracellular 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 cells.
Lacroix A.&Hontela A. 2006; Raynal et al. 2005; Gagnon et al. 2007; Hontela et al. 2007.

5. Comparative 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 between species.
Goulet B.& Hontela A. 2003; Lacroix A.& Hontela A. 2004; Raynal et al. 2005.

Research Team

Lana Miller, PhD student

Natalie Kromrey, MSc student

Andrea Dann, MSc student

Robert Annett, MSc student

Andrea Rutledge, MSc student

Nicole Pilgrim, MSc student

Heather Bird, technician