['Inflammation is an important component of the response to traumatic brain injury (TBI). Progesterone has been shown to inhibit neuroinflammation following (TBI) and may do so through Toll-like receptor (TLR)-mediated pathways. In vitro studies indicate that 1,25-dihydroxyvitamin D(3) (VDH) may also modulate the inflammatory response through the TLR4 pathway. This study tested the hypothesis that PROG and VDH would exert additive and synergistic neuroprotective effects compared with individual treatment by modulating TLR4/NF-κB-mediated inflammation pathways after TBI in rats.', 'Bilateral medial frontal cortical impact injury was induced in young adult Sprague-Dawley rats. Progesterone (i.p., 16\u2009mg\u2009kg', 'TLR4, phosphorylation of NF-κB, neuronal loss and astrocyte activation were significantly reduced with combination treatment after TBI compared to each agent given individually.'] Does progesterone and vitamin D combination therapy modulate inflammatory response after traumatic brain injury?