Hexavalent Chromium Exposure Disrupts Cardiac Development in Chicken Embryos Through Oxidative Stress and Activation...

Hexavalent chromium [Cr(VI)] is a pervasive environmental contaminant with well-documented toxicological effects across biological systems, yet its impact on early cardiac development within ecologically relevant exposure contexts remains insufficiently explored. The present study investigated the effects of in ovo Cr(VI) exposure on cardiac development in chicken embryos, integrating molecular toxicology findings with broader implications for biodiversity conservation and environmental sustainability. Environmental relevance was confirmed by detecting significantly elevated chromium concentrations in eggs collected from industrial regions (0.122-0.202 mg/kg) compared with poultry farm controls. Embryos exposed to 0.7 µg and 1.4 µg Cr(VI) per egg exhibited dose-dependent reductions in survival and crown-rump length, indicating developmental toxicity. Biochemical assessments revealed pronounced oxidative stress, characterized by increased lipid peroxidation (65-84%), substantial glutathione depletion (30-70%), and decreased antioxidant vitamins (A, C, and E), accompanied by reduced activities of key antioxidant enzymes (SOD, CAT, GPx) at embryonic day 14. Elevated serum CK-MB levels confirmed myocardial injury. Molecular analyses demonstrated significant upregulation of TGF-β1 and COL3A1 transcripts, correlating with increased hydroxyproline content and collagen deposition in cardiac tissue, as validated by Sirius Red staining, thereby indicating fibrotic remodeling mediated through the TGF-β1/COL3A1 axis. Collectively, these findings demonstrate that environmentally relevant Cr(VI) exposure disrupts embryonic cardiac development through oxidative and profibrotic mechanisms. The study underscores the ecological risks posed by heavy-metal contamination to avian species and highlights the importance of environmental monitoring and sustainable industrial practices to protect biodiversity and ecosystem health.