Feeding mice with diets containing mercury-contaminated fish flesh from French Guiana: a model for the mercurial intoxication of the Wayana Amerindians.
BACKGROUND
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 microg/g). To determine whether this mercurial contamination was harmful, mice have been fed diets prepared by incorporation of mercury-polluted fish from French Guiana.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Bourdineaud
Jean-Paul
JP
Université de Bordeaux 1-CNRS UMR 5805, Station Marine d'Arcachon, place du Docteur Peyneau, Arcachon, France. jp.bourdineaud@epoc.u-bordeaux1.fr
Bellance
Nadège
N
Bénard
Giovani
G
Brèthes
Daniel
D
Fujimura
Masatake
M
Gonzalez
Patrice
P
Marighetto
Aline
A
Maury-Brachet
Régine
R
Mormède
Cécile
C
Pédron
Vanessa
V
Philippin
Jean-Nicolas
JN
Rossignol
Rodrigue
R
Rostène
William
W
Sawada
Masumi
M
Laclau
Muriel
M
D000328:Adult; D000818:Animals; D001007:Anxiety / Q000139:chemically induced; D004195:Disease Models, Animal; D005260:Female; D005399:Fishes; D005506:Food Contamination; D005616:French Guiana; D015870:Gene Expression; D006801:Humans; D007199:Indians, South American; D008297:Male; D008630:Mercury Poisoning / Q000209:etiology* / Q000235:genetics / Q000378:metabolism; D008767:Methylmercury Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000506:poisoning* / Q000633:toxicity*; D051379:Mice; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism; D009154:Mutation; D010101:Oxygen Consumption / Q000187:drug effects
D008767:Methylmercury Compounds