Dendritic nicotinic receptors modulate backpropagating action potentials and long-term plasticity of interneurons

Stratum radiatum interneurons, unlike pyramidal cells, are rich in nicotinic acetylcholine receptors (nAChRs); however, the role of these receptors in plasticity has remained elusive. As opposed to previous physiological studies, we found that functional α7-subunit-containing nAChRs (α7-nAChRs) are abundant on interneuron dendrites of rats. Moreover, dendritic Ca2+ transients induced by activation of α7-nAChRs increase as a function of distance from soma. The activation of these extrasynaptic α7-nAChRs by cholinergic agonists either facilitated or depressed backpropagating action potentials, depending on the timing of α7-nAChR activation. We have previously shown that dendritic α7-nAChRs are involved in the regulation of synaptic transmission, suggesting that α7-nAChRs may play an important role in the regulation of the spike timing-dependent plasticity. Here we provide evidence that long-term potentiation is indeed boosted by stimulation of dendritic α7-nAChRs. Our results suggest a new mechanism for a cholinergic switch in memory encoding and retrieval