Feeding mice with diets containing mercury-contaminated fish flesh from French Guiana:
a model for the mercurial intoxication of the Wayana Amerindians
(Published : 29 October 2008)
Jean-Paul Bourdineaud(1), Nadège Bellance(2), Giovani Bénard(2), Daniel Brèthes(3), Masatake Fujimura(4), Patrice Gonzalez(1), Aline Marighetto(5), Régine Maury-Brachet(1), Cécile Mormède(5), Vanessa Pédron(1), Jean-Nicolas Philippin(5), Rodrigue Rossignol(2), William Rostène(6), Masumi Sawada(4) and Muriel Laclau(1),(3),(5)
- (1) Université de Bordeaux 1-CNRS UMR 5805, Station Marine d'Arcachon, place du Docteur Peyneau, Arcachon, 33120, France
- (2) Physiopathologie Mitochondriale, Université Victor Segalen Bordeaux2-INSERM U688, 146 rue Léo Saignat, Bordeaux, 33076 cedex, France
- (3) Institut de Biochimie et Génétique Cellulaires, Université Victor Segalen Bordeaux 2, 1 rue Camille Saint-Saëns, Bordeaux, 33077 cedex, France
- (4) National Institute for Minamata Disease, Pathology Section, Department of Basic Medical Sciences, 4058-18 Hama, Minamata, Kumamoto 867-0008, Japan
- (5) Laboratoire de Neurosciences Cognitives, Université de Bordeaux 1-CNRS UMR 5106, Avenue des Facultés, Talence, 33405, France
- (6) Centre de Recherches Saint-Antoine, INSERM U732, Hôpital Saint-Antoine, 184 rue du Faubourg Saint-Antoine, Paris, 75571 cedex 12, France
In 2005, 84% of Wayana Amerindians living in the upper marshes of the Maroni River in French Guiana presented a hair mercury concentration exceeding the limit set up by the World Health Organization (10 µg/g). To determine whether this mercurial contamination was harmful, mice have been fed diets prepared by incorporation of mercury-polluted fish from French Guiana.
Four diets containing 0, 0.1, 1, and 7.5% fish flesh, representing 0, 5, 62, and 520 ng methylmercury per g, respectively, were given to four groups of mice for a month. The lowest fish regimen led to a mercurial contamination pressure of 1 ng mercury per day per g of body weight, which is precisely that affecting the Wayana Amerindians.
The expression of several genes was modified with mercury intoxication in liver, kidneys, and hippocampus, even at the lowest tested fish regimen. A net genetic response could be observed for mercury concentrations accumulated within tissues as weak as 0.15 ppm in the liver, 1.4 ppm in the kidneys, and 0.4 ppm in the hippocampus. This last value is in the range of the mercury concentrations found in the brains of chronically exposed patients in the Minamata region or in brains from heavy fish consumers. Mitochondrial respiratory rates showed a 35-40% decrease in respiration for the three contaminated mice groups. In the muscles of mice fed the lightest fish-containing diet, cytochrome c oxidase activity was decreased to 45% of that of the control muscles. When mice behavior was assessed in a cross maze, those fed the lowest and mid-level fish-containing diets developed higher anxiety state behaviors compared to mice fed with control diet.
We conclude that a vegetarian diet containing as little as 0.1% of mercury-contaminated fish is able to trigger in mice, after only one month of exposure, disorders presenting all the hallmarks of mercurial contamination.