Diclofenac in fish: Blood plasma levels similar to human therapeutic levels affect global hepatic gene expression

Abstract

Diclofenac is a nonsteroidal anti-inflammatory drug frequently found in the aquatic environment. Previous studies have reported histological changes in the liver, kidney, and gills of fish at concentrations similar to those measured in treated sewage effluents (approximately 1 µg/L). Analyses or predictions of blood plasma levels in fish allow a direct comparison with human therapeutic plasma levels and may therefore be used to indicate a risk for pharmacological effects in fish. To relate internal exposure to a pharmacological interaction, we investigated global hepatic gene expression together with bioconcentration in blood plasma and liver of rainbow trout (Oncorhynchus mykiss) exposed to waterborne diclofenac. At the highest exposure concentration (81.5 µg/L), the fish plasma concentration reached approximately 88% of the human therapeutic levels (C(max) ) after two weeks. Using an oligonucleotide microarray followed by quantitative PCR, we found extensive effects on hepatic gene expression at this concentration, and some genes were found to be regulated down to the lowest exposure concentration tested (1.6 µg/L), corresponding to a plasma concentration approximately 1.5% of the human C(max) . Thus, at concentrations detected in European surface waters, diclofenac can affect the expression of multiple genes in exposed fish. Functional analysis of differentially expressed genes revealed effects on biological processes such as inflammation and the immune response, in agreement with the mode of action of diclofenac in mammals. In contrast to some previously reported results, the bioconcentration factor was found to be stable (4.02 ± 0.75 for blood plasma and 2.54 ± 0.36 for liver) regardless of the water concentration.

Behavioral and biochemical responses in freshwater fish Carassius auratus exposed to sertraline

“…This approach is based on receptor homology and other pathway similarities between fish and mammals (Valenti et al, 2012;Margiotta-Casaluci et al, 2014). A study by Cuklev et al (2011) specifically addressed the relationship between blood plasma levels of diclofenac in fish and effects on the molecular level; effects were discernible when plasma levels in the fish approached human therapeutic concentration (H T PC). Valenti et al (2012) observed significant decreases in binding at the therapeutic target and shelter-seeking behavior when fish plasma levels of sertraline exceeded H T PC, which was defined as either 142 ng mL À1 or 190 ng mL À1 .…”

Does ketoprofen or diclofenac pose the lowest risk to fish?

“…Several studies have reported effects on fish at these concentrations of diclofenac, ranging from cytological and histological effects [14][15][16][17] to effects on gene expression [15,18]. Reported bioconcentration factors (BCFs) for diclofenac in rainbow trout varies between studies [10,11,16,18,19].…”

“…Reported bioconcentration factors (BCFs) for diclofenac in rainbow trout varies between studies [10,11,16,18,19]. However, the most recent studies are in relatively close agreement, showing a stable BCF from water to blood plasma of approximately 4 [18,19]. We have recently shown effects on the global hepatic gene expression at exposure concentrations of diclofenac down to 1.6 g/L, even though the corresponding plasma concentration of exposed fish was relatively low (approximately 6 ng/mL) in comparison with the human therapeutic plasma concentrations (HTPC) of >420 ng/mL [20,21].…”

Effects of pharmaceuticals present in aquatic environment on Phase I metabolism in fish

“…Recent evidence suggests that diclofenac has the potential to cause adverse effects in various fish organs at an environmentally relevant concentration (Triebskorn et al, 2004). Diclofenac also affected gene expression in rainbow trout at 1 µg/L (Cuklev et al, 2011), and it activated VTG and CYP1A expression at 1 µg/L (Hong et al, 2007) and changed feeding behavior at 1000 µg/L (Nassef et al, 2010) in Japanese medaka. Contrary to these investigations, no observed effects were seen at concentrations of 320 µg/L in rainbow trout after 95 days' exposure (Memmert et al, 2013).…”