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Research article2017Peer reviewed

Diclofenac affects kidney histology in the three-spined stickleback (Gasterosteus aculeatus) at low μg/L concentrations

Naslund, Johanna; Fick, Jerker; Asker, Noomi; Ekman, Elisabet; Larsson, D. G. Joakim; Norrgren, Leif

Abstract

Diclofenac, a commonly used non-steroidal anti-inflammatory drug, is considered for regulation under the European water framework directive. This is because effects on fish have been reported at concentrations around those regularly found in treated sewage effluents (similar to 1 mu g/L). However, a recent publication reports no effects on fish at 320 mu g/L. In this study, three-spined sticklebacks (Gasterosteus aculeatus) were exposed to 0, 4.6, 22, 82 and 271 mu g/L diclofenac in flow-through systems for 28 days using triplicate aquaria per concentration. At the highest concentration, significant mortalities were observed already after 21 days (no mortalities found up to 22 mu g/L). Histological analysis revealed a significant increase in the proportion of renal hematopoietic tissue (renal hematopoietic hyperplasia) after 28 days at the lowest concentration and at all higher concentrations, following a clear dose-response pattern. Skin ulcerations of the jaw were noted by macroscopic observations, primarily at the two highest concentrations. No histological changes were observed in the liver. There was an increase in the relative hepatic mRNA levels of c7 (complement component 7), a gene involved in the innate immune system, at 22 mu g/L and at all higher concentrations, again following a clear dose-response. The bio-concentration factor was stable across concentrations, but lower than reported for rainbow trout, suggesting lower internal exposure to the drug in the stickleback. In conclusion, this study demonstrates that diclofenac causes histological changes in the three-spined stickleback at low mu g/L concentrations, which cause concern for fish populations exposed to treated sewage effluents.

Keywords

Diclofenac; Fish; Histology; Kidney; Quantitative PCR; Bioconcentration

Published in

Aquatic Toxicology
2017, Volume: 189, pages: 87-96
Publisher: ELSEVIER SCIENCE BV