Akademik Veri Yönetim Sistemi
Ecotoxicology, cilt.34, sa.10, ss.2101-2111, 2025 (SCI-Expanded, Scopus)
The increasing prevalence of titanium dioxide nanoparticles (nTiO₂) in aquatic environments, coupled with rising global climate change, presents critical challenges to aquatic organisms. This study investigates in vivo the effects of bulk and nTiO₂ exposure at normal (25 °C) and elevated temperature level (33 °C) for 96 h on oxidative stress markers, ABC transporter expression, and hsp90 regulation in liver of goldfish (Carassius auratus). Oxidative stress was assessed via catalase (CAT) activity, glutathione S-transferase (GST) activity, and reactive oxygen species (ROS) generation and demonstrated significant alterations under the effect of the combined stressors. Notably, nTiO₂ elicited higher oxidative stress than bulk TiO₂ (bTiO2) despite lower tissue accumulation, particularly at elevated temperature. Under stress, Real Time PCR analysis revealed different modulation patterns of ABC transporters (ABCB1, ABCC1, ABCC2) and HSP90, both in terms of concentration- and temperature-dependent responses. The notable downregulation of abcc1 and hsp90 in the nTiO₂ group at 33 °C would suggest a compromised cellular stress response, possibly reflecting insufficient activation of protective mechanisms at the transcriptional level. Although high temperature appeared to reduce total ROS generation, it also caused GST depletion, indicating an alteration in antioxidant defense dynamics. On the other hand, bTiO₂ may have reduced oxidative stress by means of hsp90 upregulation, so promoting a more stable antioxidant response even if its accumulation at high temperature is significantly higher. These findings highlight the combined effects of nanoparticle exposure and thermal stress on oxidative defenses and detoxification pathways in aquatic organisms. The study underscores the need to assess nanoparticles pollution in the context of climate change, providing insights into molecular mechanisms underlying stress responses in fish.