iTRAQ-based quantitative proteomic analysis reveals the toxic mechanism of diclofenac sodium on the kidney of broiler chicken.

Diclofenac sodium (DS) is one of the nonsteroidal anti-inflammatory drugs (NSAIDs), which exhibits potent toxicity to birds. To search the molecular mechanism of DS induced nephrotoxicity in broiler chicken, 20 apparently healthy 30-day old broiler chickens were separated randomly into two groups (n = 10): Group A was kept as control while DS was administered at the dose rate of 10 mg/kg body weight in group B through oral gavage. Kidney samples were collected, and the proteins were identified and quantified by iTRAQ. 434 differentially expressed proteins (DEPs) were screened, including 277 up-regulated DEPs and 157 down-regulated DEPs. The functional annotation and classification results indicated that DEPs were significantly enriched in apoptosis and metabolism-related pathways via GO and KEGG analysis. Compared with the control group, the most significant enrichment pathways are "ribosome", "metabolic pathways" and "protein processing in endoplasmic reticulum". Based on the proteomic results and relevant literature, some DEPs that potentially related to the toxicity of DS were screened. The mRNA transcript levels of these DEPs were characterized by qRT-PCR, and the results showed that Slc22a7, Gatm, Glud1, Agxt2 and Gldc were significantly down-regulated, while Gsl, Gpt2 and Asns were significantly up-regulated. We speculate that the toxic mechanism of DS to chicken might be that it induces kidney cell apoptosis, interferes with purine metabolism and inhibits the expression of OAT2. The current study provides a reference for elucidating the nephrotoxic mechanism of diclofenac sodium to broiler chicken from the molecular perspective.