Rat Interleukin-1 Alpha (IL-1α) is a pro-inflammatory cytokine belonging to the IL-1 family—which includes IL-1α, IL-1β, and the IL-1 receptor antagonist (IL-1Ra)—and plays a central role in initiating innate and sterile inflammatory responses in rats (Rattus norvegicus). IL-1α is constitutively expressed in epithelial, endothelial, and barrier tissues and functions as an intracellular alarmin that is rapidly released upon cell injury, necrosis, ischemia, or toxic insult, triggering early inflammatory signaling independent of inflammasome processing. Upon binding to the IL-1 receptor type 1 (IL-1R1), rat IL-1α activates NF-κB and MAPK pathways that promote leukocyte recruitment, endothelial activation, fever, and amplification of downstream pro-inflammatory cytokine cascades. In rat models, IL-1α is widely studied in experimental systems of stroke and ischemia–reperfusion injury, traumatic brain injury, arthritis, colitis, neuropathic pain, and cancer-associated inflammation, where it contributes to early tissue inflammation and immune cell infiltration. Because rats are frequently used in pharmacology, toxicology, neuroscience, and cardiovascular research, characterization of IL-1α is critical for understanding sterile inflammation, tissue injury responses, and cytokine-driven pathology. As both a biomarker and therapeutic target, rat IL-1α supports preclinical investigation of anti-inflammatory agents and IL-1–modulating therapies relevant to human inflammatory, neurologic, and cardiovascular diseases.