Protein synthesis in dendrites plays an important role in long-lasting long-term potentiation (L-LTP)

Long-term potentiation (LTP) is a lasting increase in synaptic strength induced by synaptic activity. To last beyond 2-3 hrs, LTP necessitates synthesis of new proteins in the postsynaptic neurons. At first, it was believed that all these proteins were synthesized in the soma. However, more recently, it was proved that translation of mRNAs could also take place in dendrites. Hence the question asked here: is a dendritic protein synthesis able to sustain an LTP lasting more than 2-3 hrs ?
LTP was elicited in hippocampal slices by delivering 4 trains of stimulation to the Schaffer's collaterals while monitoring the resulting field excitatory postsynaptic potential (fEPSP) in the CA1 region for 8 hours. Taking advantage of the fact that, in CA1 pyramidal cells, it was possible to sever the dendrites from their somas, we were able to analyse LTP on isolated dendrites.
A long-lasting LTP was observed. Eight hours after induction the slope of the fEPSP was at 154 ± 13 % of its basal level. When anisomycine, an inhibitor of translation, was added, it prevented the maintenance of LTP. Eight hours after induction, the slope of fEPSP dropped to basal level (101 ± 6 %).
We conclude that local dendritic protein synthesis plays an important role in the late phase of long-lasting LTP.