ABSTRACT
The lipid regulator gemfibrozil (GEM) is one of many human pharmaceuticals found in the aquatic environment. We previously demonstrated that GEM bioconcentrates in blood and reduces plasma testosterone levels in goldfish (Carassius auratus). In this study, we address the potential of an environmentally relevant waterborne concentration of GEM (1.5 microg/l) to induce oxidative stress in goldfish liver and whether this may be linked to GEM acting as a peroxisome proliferator (PP). We also investigate the autoregulation of the peroxisome proliferator-activated receptors (PPARs) as a potential index of exposure. The three PPAR subtypes (alpha, beta, and gamma) were amplified from goldfish liver cDNA. Goldfish exposed to a concentration higher (1500 microg/l) than environmentally relevant for 14 and 28 days significantly reduce hepatic PPARbeta mRNA levels (p<0.001). Levels of CYP1A1 mRNA were unchanged. GEM exposure significantly induced the antioxidant defense enzymes catalase (p<0.001), glutathione peroxidase (p<0.001) and glutathione-S-transferase (p=0.006) but not acyl-CoA oxidase or glutathione reductase. As GEM exposure failed to increase levels of thiobarbituric reactive substances (TBARS), we conclude that a sub-chronic exposure to GEM upregulates the antioxidant defense status of the goldfish as an adaptive response to this human pharmaceutical.
Subject(s)
Antioxidants/metabolism , Gemfibrozil/toxicity , Goldfish/metabolism , Hypolipidemic Agents/toxicity , Liver/metabolism , PPAR-beta/biosynthesis , RNA, Messenger/biosynthesis , Water Pollutants, Chemical/toxicity , Actins/biosynthesis , Actins/metabolism , Acyl-CoA Oxidase/metabolism , Animals , Body Weight/drug effects , Cytochrome P-450 CYP1A1/biosynthesis , Cytochrome P-450 CYP1A1/metabolism , Down-Regulation/drug effects , Glutathione/metabolism , Lipid Peroxidation/drug effects , Liver/drug effects , Male , Molecular Sequence Data , Oxidative Stress/drug effects , Reverse Transcriptase Polymerase Chain Reaction , Thiobarbituric Acid Reactive Substances/metabolism , Tissue DistributionABSTRACT
Human and veterinarian pharmaceuticals have been detected in the aquatic environment for a number of years, but the potential for biological effects in exposed aquatic organism is only now being reported. The lipid regulator, gemfibrozil (GEM) is detected at microg/L concentrations in domestic wastewater and ng/L concentrations in surface waters. We investigated the uptake of GEM in goldfish (Carassius auratus) over a 96 h time period by measuring GEM in blood plasma using LC-MS/MS. Results indicated that GEM can be taken up from water through the gills. In goldfish exposed to GEM by a single intraperitoneal injection, concentrations of GEM in the blood plasma declined rapidly over 96 h post-injection, with a half-life estimated at approximately 19 h. Exposure of goldfish to waterborne GEM at an environmentally relevant concentration over 14 days resulted in a plasma bioconcentration factor of 113. In goldfish exposed to aqueous concentrations of GEM for 96 h or 14 days, plasma testosterone (T) was reduced by over 50% in fish from all treatments. As a possible mechanistic explanation for the observed reduction in T, levels of steroid acute regulatory (StAR) protein transcript in goldfish testes were assessed by RT-PCR. StAR protein is involved in the transport of cholesterol from the outer to the inner mitochondrial membrane for transformation by the first enzyme in steroidogenesis. After exposure to GEM for 96 h, a 50% decrease in StAR mRNA levels was observed in goldfish. Gonadal StAR mRNA levels were not affected in the 14 days exposure, indicating that the observed decreases in plasma testosterone were not solely due to impaired delivery of cholesterol to the inner mitochondrial membrane. Our results demonstrate that exposure to environmental levels of GEM leads to bioconcentration of the drug in plasma and the potential for endocrine disruption in fish.
