Synaptic NF-kappa B pathway in neuronal plasticity and memory

•NF-kappa B is present at the synapses.•After activation NF-kappa B can retrogradely be transported to the nucleus.•NF-kappa B may also have a local role at the synapses.•Synaptic NF-kappa B translocates to the membranes during memory consolidation.•Local NF-kappa B may recruit post-translational modifying proteins.

Several transcription factors are present at the synapse, and among these are the Rel-NF-kappa B pathway components. NF-kappa B is a constitutive transcription factor, with a strong presence in the brain of which a considerable part is located in the neuropiles.This localization of the transcription factor, plus evidence pointing to different functions, is what gave place to two general hypotheses for synaptic NF-kappa B: (a) The transcription factor plays a role in the synapse to nucleus communication, and it is retrogradely transported from polarized localizations to regulate gene expression; (b) The transcription factor modulates the synaptic function locally. Evidence indicates that both mechanisms can operate simultaneously; here we will present different possibilities of these hypotheses that are supported by an increasing amount of data. We pay special attention to the local role of the transcription factor at the synapse, and based in the described evidence from different animal models, we propose several processes in which the transcription factor may change the synaptic strength.