Diethyl Phthalate-Induced Oxidative Stress, Altered Biomarker Responses and Apoptosis in Zebrafish Larvae

Diethyl phthalate (DEP) is a widespread and persistent organic pollutant that affects aquatic life and ecosystems. Our study uses zebrafish larvae to assess the effects of DEP on metabolic pathways involved in growth and development. Zebrafish larvae exposed to DEP showed an increased mortality rate of 97% and a reduced hatching rate of 37% at the highest concentration. Also, exposure to DEP caused an increased heartbeat compared to the untreated control, indicating DEP-induced developmental toxicity. Moreover, elevated ROS levels and significant changes in other biomarkers like SOD, CAT, GPx, GST, LDH, AP, GSH, LPO, and NO at the highest concentration indicate severe oxidative stress. Similarly, significant changes in AChE activity and cortisol levels denote neurochemical alterations and stress in treated larvae. Higher levels of ALT and AST were also observed in the larvae treated with DEP, indicating that the exposure causes changes in the activity of liver enzymes. DEP also causes cell death, which leads to increased apoptotic rates in the treated larvae compared to the untreated control. Also, elevated levels of caspase-3, 8 and 9, which are key regulators of the apoptosis pathway, were observed in larvae treated with the highest concentration of DEP. Furthermore, expression analysis revealed the downregulation of the anti-apoptotic gene BCl2 and the upregulation of the pro-apoptotic gene Bax, confirming apoptosis induction in DEP treated larvae. In conclusion, our study highlights the toxicological effects of DEP on various cellular pathways and the alarming concern about its potential impacts on the ecosystem and human health.