Quercetin attenuates endocrine and metabolic responses to oxytetracycline in silver catfish (Rhamdia quelen)

The antibacterials ciprofloxacin, trimethoprim and sulfadiazine modulate gene expression, biomarkers and metabolites associated with stress and growth in gilthead sea bream (Sparus aurata)

The high consumption and subsequent input of antibacterial compounds in marine ecosystems has become a worldwide problem. Their continuous presence in these ecosystems allows a direct interaction with aquatic organisms and can cause negative effects over time. The objective of the present study was to evaluate the effects of exposure to three antibacterial compounds of high consumption and presence in marine ecosystems (Ciprofloxacin CIP, Sulfadiazine SULF and Trimethoprim TRIM) on the physiology of the gilthead sea bream, Sparus aurata. Plasma parameters, enzymatic biomarkers of oxidative stress and damage and expression of genes related to stress and growth were assessed in exposed S. aurata specimens. For this purpose, sea bream specimens were exposed to individual compounds at concentrations of 5.2 ± 2.1 μg L^-1 for CIP, 3.8 ± 2.7 μg L^-1 for SULF and 25.7 ± 10.8 μg L^-1 for TRIM during 21 days. Exposure to CIP up-regulated transcription of genes associated with the hypothalamic-pituitary-thyroid (HPT) (thyrotropin-releasing hormone, trh) and hypothalamic-pituitary-interrenal (HPI) axes (corticotropin-releasing hormone-binding protein, crhbp) in the brain, as well as altering several hepatic stress biomarkers (catalase, CAT; glutathione reductase, GR; and lipid peroxidation, LPO). Similar alterations at the hepatic level were observed after exposure to TRIM. Overall, our study indicates that S. aurata is vulnerable to environmentally relevant concentrations of CIP and TRIM and that their exposure could lead to a stress situation, altering the activity of antioxidant defense mechanisms as well as the activity of HPT and HPI axes.

Effects of exposure to oxytetracycline on the liver proteome of red seabream (Pagrus major) in a real administration scenario

Oxytetracycline (OTC) is a widely used antibiotic in aquaculture. In this study, red seabream (Pagrus major), the most popular aquaculture species in Japan, were treated with OTC mimicking a real administration scenario in aquaculture. The treatment groups were as follows: no OTC, 40 mg/kg body wt/day (equivalent to the dose used in actual aquaculture), or 178 mg/kg body wt/day. The first exposure was conducted for a week (1st OTC exposure period), followed by a 4-week interval, and the second exposure was for one week (2nd OTC exposure period). We investigated the effects of OTC on the liver proteome with the isobaric tags for relative and absolute quantitation (iTRAQ) technology accompanied by liquid chromatography and mass spectrometry. The pathway and disease enrichment analyses of differentially abundant proteins in OTC-exposed groups compared to their respective controls showed that the abundance of proteins related to the immune and nervous systems was altered after the 1st and 2nd OTC exposures, respectively. Quantitative real-time PCR of the transcripts of immune-related genes corroborated with the results of proteome analysis. OTC exposure also modulated the expression of metabolism-related proteins after the 1st and 2nd OTC exposures. Furthermore, after four weeks of the 2nd exposure, weight loss and changes in the expression of proteins related to metabolism were observed, suggesting that OTC exposure disrupts the metabolic system and causes growth inhibition. Based on these results, we suggest that the use of OTC in aquaculture poses a health risk in fish species. Thus, we need to pay more attention to the contamination with OTC in aquaculture.