TNF and necrotizing enterocolitis: Additionally, a model in which mouse pups were stressed with hyperosmolar formula, hypoxia, and lipopolysaccharide (LPS) to induce NEC demonstrated that pups exposed to NEC stress had smaller brains associated with increased apoptosis, decreased numbers of neurons, and increased levels of the proinflammatory mediators IL-6 and tumor necrosis factor alpha [19].