Rat CCL2 (C-C motif chemokine ligand 2, also known as monocyte chemoattractant protein-1, MCP-1) is a pro-inflammatory chemokine that plays a central role in recruitment and activation of monocytes, macrophages, and memory T cells during immune responses in rats (Rattus norvegicus). CCL2 signals primarily through the CCR2 receptor, activating intracellular pathways that promote leukocyte migration, cytokine production, and coordination of innate and adaptive immune responses at sites of infection, tissue injury, or inflammation. In rat research, CCL2 is widely studied in experimental models of neuroinflammation, cardiovascular disease, metabolic disorders, and kidney injury, where monocyte and macrophage infiltration contributes to tissue remodeling and disease progression. Rat CCL2 is also important in neuropathic pain and central nervous system injury models, where it mediates recruitment of immune cells to the brain and spinal cord and influences neuroimmune signaling. While CCL2-driven immune cell trafficking supports host defense and tissue repair, excessive or sustained expression can promote chronic inflammation and tissue damage. Because rats are widely used in pharmacology, neuroscience, and cardiovascular research, characterization of rat CCL2 supports investigations into chemokine-mediated immune regulation, inflammatory disease mechanisms, and development of targeted anti-inflammatory therapies relevant to human disease.