Toxic effects of dibutyl phthalate on testes of adult zebrafish: evaluation of oxidative stress parameters and histopathology.

ABSTRACT

Dibutyl phthalate (DBP) is a phthalic compound and is most commonly used as a plasticizer in the polymer industry. It affects the hypothalamus-pituitary-gonadal axis and produces infertility in exposed animals. A total of 366 adult male zebrafish were used to evaluate the toxicological effects of DBP in testes following continuous exposure for 28 days. To evaluate histological changes during phase I of the study, 30 zebrafish were equally divided into five groups viz., control (RO water), vehicle control (0.01% DMSO), T0 (250 µg/L of water), T1 (500 µg/L of water), and T2 group (1000 µg/L of water). The protocol for phase II of the study was decided based on the results of phase I of the study. During phase II, for evaluation of oxidative stress parameters and gene expression profile, a total of 336 fish were equally divided into four groups viz., control, vehicle control, T1 (500 µg/L of water), and T2 (1000 µg/L of water). The activity of SOD, CAT, and TAC was significantly lower in zebrafish from the T2 group; however, a significantly increased level of MDA in the T2 group was recorded as compared to control groups. mRNA expression profile of sod, cat, and nrf2 genes was significantly downregulated in the T2 group as compared to the control group. Histopathology and proliferating cell nuclear antigen immunostaining revealed a reduction in spermatozoa with increased spermatocytes and spermatogonia in testes from T1 and T2 groups. The result indicated that DBP can induce oxidative stress and affect spermatogenesis in zebrafish testes.