The use of dietary probiotics in long-term exposure to treat the effect of the nonsteroidal anti-inflammatory drug (NSAID) naproxen causes thyroid dysfunction in zebrafish (Danio rerio)

Naproxen (NPX) is a nonsteroidal anti-inflammatory drug (NSAID) that has been identified in aquatic environments. It has led to growing concerns about endocrine disruption in aquatic organisms exposed to its drug residues. This study aimed to evaluate the disruptive effects of NPX and the improving effects of probiotic nutrition on thyroid, and zebrafish growth. The fish were fed for 60 days by basic diet (TN, Control) basic diet with probiotics (TP, TPN) (Lactobacillus reuteri, CFU/1.5×108) and simultaneously exposed to NPX (100 μg/L) (TN, TPN). During the experiment, Triiodothyronine (T3), Thyroxine (T4), Thyroid-stimulating hormone (TSH), Iodothyronine Deiodinase-1 (DIO1), and Iodothyronine Deiodinase-2 (DIO2), in addition to growth rate factors were evaluated with ELISA and Quantitative real-time PCR assay. The results showed probiotic feeding and NPX exposure did not affect T3 levels (p>0.05), but decreased T4 (p<0.05). TSH gene transcription expression increased as a result of probiotic feeding and NPX exposure (p<0.05) while DIO1 and DIO2 gene expression decreased (p<0.05). Weight gain and growth rate were also observed as a result of probiotic feeding, while exposure to NPX decreased growth rate (p<0.05). Generally, the results showed that NPX increased the risk of thyroid dysfunction and reduced growth rate in zebrafish, while probiotic feeding improved these factors. Therefore, the use of probiotic supplements in rearing centers is recommended due to the continuous increase in the consumption and distribution of drugs. Prolonged exposure to drug concentrations causes thyroid dysfunction and consequently reduced growth in fish, which will lead to significant economic losses.