Impaired acute and inflammatory nociception in mice lacking the p50 subunit of NF-κB

The transcription factor NF-κB is thought to play an essential role in inflammatory processes and pain. However, the in vivo function of individual NF-κB subunits in the development and processing of nociceptive responses is not clarified. In this study we investigated the role of the p50 subunit of NF-κB in models of acute and persistent nociception using NF-κB p50−/− mice. We found that these mice showed impaired basal responses to mechanical as well as thermal noxious stimulation in the dynamic plantar as well as the hot plate test, respectively, in comparison with wild-type mice. In the formalin test we observed a decreased nociceptive behavior in the first and the second phase in NF-κB p50−/− mice. In a model of persistent inflammatory hyperalgesia these mice also showed a reduced hyperalgesia to a thermal stimulus, which was in accordance with a lower cyclooxygenase-2 expression in the spinal cord after peripheral inflammatory stimulation. Taken together, our data indicate that the p50 subunit of NF-κB is of importance in acute and persistent inflammatory pain. The participation to persistent pain might rely on activation of NF-κB by inflammatory stimuli while the contribution to acute pain responses might be related to constitutive NF-κB activity in neurons of the nociceptive system.