Acute effects of diclofenac and DMSO to Daphnia magna: immobilisation and hsp70-induction.
To determine the toxicity of the anti-rheumatic drug diclofenac to Daphnia magna, acute toxicity tests according to the OECD guideline 202 were combined with biochemical investigations of the hsp70 level as a biomarker for proteotoxicity. Particular attention was paid to the impact of the solvent DMSO as a confounding factor to diclofenac toxicity by means of testing different variations of producing stock solutions. In the acute immobilisation tests, diclofenac was most toxic as a singular test substance, with indication of a slight antagonistic interaction between the two substances. The highest EC50 values were obtained in those approaches using diclofenac pre-dissolved in DMSO. Thus, the observed antagonism seems to be intensified by pre-dissolution. Hsp70 levels of 12- to 19-days-old D. magna were determined after 48h exposure using a highly reproducible immunological protocol. Hsp70 induction occurred at a LOEC of 30mgl(-1) diclofenac plus 0.6mll(-1) DMSO, and at a LOEC of 40mgl(-1) for diclofenac alone. In summary, DMSO showed only slight confounding effects on diclofenac action in the applied range of concentrations.
Haap
Timo
T
Animal Physiological Ecology, University of Tübingen, Konrad-Adenauer-Street 20, D-72072 Tübingen, Germany. timo.haap@uni-tuebingen.de
Triebskorn
Rita
R
Köhler
Heinz-R
HR
D000818:Animals; D018501:Antirheumatic Agents / Q000633:toxicity*; D003621:Daphnia / Q000187:drug effects*; D004008:Diclofenac / Q000633:toxicity*; D004121:Dimethyl Sulfoxide / Q000633:toxicity*; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D018501:Antirheumatic Agents; D018840:HSP70 Heat-Shock Proteins; D014874:Water Pollutants, Chemical; D004008:Diclofenac; D004121:Dimethyl Sulfoxide