A simple oral STZ/alloxan-induced diabetic zebrafish model for chronic wound healing and therapeutic assessment

Reliable long-term vertebrate models that recapitulate diabetic chronic wound pathology while minimizing procedural stress remain limited. Here, we establish a non-invasive continuous oral streptozotocin (STZ)/alloxan-induced diabetic adult Danio rerio model optimized for chronic skin wound healing research. Unlike intraperitoneal (I.P.) injection, which causes stress, behavioral impairment, and early mortality, oral administration improves survival and preserves locomotion, making it suitable for long-term wound-healing studies. Although I.P. injection effectively induces hyperglycemia, its cumulative physiological burden restricts long-term monitoring of chronic wound progression, where sustained viability and behavioral stability are essential. Systematic comparison of administration routes demonstrated that I.P. injection caused hypoactivity, reduced behavioral complexity, and high mortality, limiting survival to late healing stages. In contrast, oral delivery of STZ and alloxan in optimized solvents (citrate buffer and saline) maintained a stable diabetic phenotype while minimizing systemic stress and mortality. Among tested formulations, the STZ:alloxan combination produced the most robust chronic wound profile, characterized by significantly delayed wound closure kinetics without compromising long-term viability. Integration with a reproducible laser-based full-thickness skin ablation system further enhanced experimental consistency while adhering to refinement principles. Multidimensional 3D locomotion profiling and principal component analysis revealed that behavioral divergence was primarily driven by injection-related stress rather than hyperglycemia itself, underscoring the importance of administration route selection in chronic studies. Transcriptomic analysis at 10 days post-injury showed sustained inflammatory activation in diabetic wounds, with enrichment of interleukin-6 and interferon signaling pathways, alongside suppression of ribosome biogenesis, cell-cycle progression, and proliferative programs, indicating a chronic inflammatory arrest state that impairs regeneration. Notably, metformin treatment partially restored proliferative and metabolic pathways while attenuating excessive inflammation, confirming therapeutic responsiveness. Collectively, this study presents a scalable, ethically refined vertebrate platform that decouples diabetogenic efficacy from procedural stress, enabling reliable long-term mechanistic investigation and translational screening for diabetic chronic wounds.