Effects of agricultural pesticides on the immune system of Rana pipiens and on its resistance to parasitic infection.
In the past 30 years, many amphibian species have suffered population declines throughout the world. Mass mortality have been frequently reported, and in several instances, infectious diseases appear to be the cause of death. The role that contaminants could play in these die-offs through immunotoxic effects has been poorly investigated. In this study, juvenile leopard frogs (Rana pipiens) were exposed for 21 d to a mixture of six pesticides (atrazine, metribuzin, aldicarb, endosulfane, lindane, and dieldrin) and subsequently challenged with a parasitic nematode, Rhabdias ranae. Exposure to the mixture at environmentally realistic concentrations significantly reduced lymphocyte proliferation. Three weeks after the end of the exposure, lymphocyte proliferation had recovered and was stimulated in frogs challenged with parasites with the exception of those previously exposed to the highest concentration. No pesticide effects on phagocytosis and splenocyte numbers were detectable at the end of the exposure period, but these two parameters were diminished 21 d after the infection challenge in frogs previously exposed to the highest levels of pesticides. In these animals, the prevalence of lung infection by R. ranae also tended to be higher. These results suggest that agricultural pesticides can alter the immune response of frogs and affect their ability to deal with parasitic infection.
Christin
Marie-Soleil
MS
INRS-Institut Armand-Frappier-Santé humaine, 245 Hymus Boulevard, Pointe-Claire, Quebec H9R 1G6, Canada.
Gendron
Andrée D
AD
Brousseau
Pauline
P
Ménard
Lucie
L
Marcogliese
David J
DJ
Cyr
Daniel
D
Ruby
Sylvia
S
Fournier
Michel
M
D000383:Agriculture; D000704:Analysis of Variance; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D004198:Disease Susceptibility; D004306:Dose-Response Relationship, Immunologic; D004781:Environmental Exposure / Q000032:analysis; D008213:Lymphocyte Activation / Q000187:drug effects; D009349:Nematode Infections / Q000276:immunology / Q000469:parasitology*; D010575:Pesticides / Q000633:toxicity*; D010587:Phagocytosis / Q000187:drug effects; D011894:Rana pipiens / Q000276:immunology* / Q000469:parasitology*; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000009:adverse effects
D010575:Pesticides; D014874:Water Pollutants, Chemical