INCREASED EXPRESSION OF DENDRITIC MESSENGER-RNA FOLLOWING THE INDUCTION OF LONG-TERM POTENTIATION

A small number of mRNAs, including Ca2+/calmodulin-dependent protein k inase II cr-subunit (CamKII alpha) mRNA and microtubule-associated pro tein 2 (MAP2) mRNA, are present in the dendrites of neurones as well a s in the cell bodies. We show here that the induction of long-term pot entiation (LTP) in the hippocampal perforant path/granule cell synapse s in anaesthetised rats is associated with increased levels of CamKII alpha mRNA and MAP;! mRNA in the granule cell dendrites after 2 h. Sim ilarly, induction of LTP in the Schaffer collateral/CAl pyramidal cell synapses in hippocampal slices maintained in vitro also results in el evated dendritic levels of CamKII alpha: mRNA and MAP;! mRNA 2 h later . In both models, the levels of various other mRNA species restricted to the cell body region were unaffected by the induction of LTP. Incre ased expression of dendritic CamKII alpha mRNA and MAP2 mRNA appears t o be a general feature of hippocampal plasticity, since it occurs foll owing LTP induction in both the dentate gyrus and the CA1 region. The elevation of mRNA levels in a restricted region close to the afferent synapses would allow a highly-localised enhancement of the synthesis o f the corresponding proteins, providing an elegant mechanism for prote in-synthesis-dependent synaptic plasticity to maintain a high degree o f anatomical specificity. (C) 1998 Elsevier Science B.V.