Drosophila melanogaster as a Model for Gastrointestinal Radiation Injury: Conserved Mechanisms, Experimental Approaches, and Countermeasure Discovery.

The gastrointestinal tract is a critical target of acute radiation exposure. Severe radiation exposure can deplete epithelial stem and progenitor cells, compromise barrier integrity, alter host-microbe interactions, and drive fluid loss, inflammation, and systemic decline. Mammalian models remain essential for clinical translation, but their cost and complexity constrain sample sizes, statistical power, large-scale mechanistic discovery, and countermeasure screening. The adult Drosophila melanogaster midgut provides a complementary in vivo platform containing intestinal stem cells, absorptive enterocytes, enteroendocrine cells, epithelial junctions, an associated microbiota, and conserved innate immune and injury-response pathways. Direct irradiation studies have demonstrated DNA damage, altered stem cell proliferation and differentiation, epithelial plasticity, apoptosis, autophagy-associated responses, morphological disruption, barrier failure, microbiome changes, and reduced survival. These phenotypes can be modulated by genotype, sex, diet, microbial status, antioxidant capacity, and regenerative signaling. This review evaluates the biological rationale, direct evidence, experimental assays, and countermeasure applications supporting the fly midgut as a model for studying gastrointestinal radiation injury. Although Drosophila has a long history of use in radiation research, our analysis indicates that the fly midgut is best positioned not as a miniature model of clinical gastrointestinal acute radiation syndrome, but as a genetically precise and scalable system for identifying conserved mechanisms and prioritizing interventions for validation in mammalian models.