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 alpha7-subunit-containing
nAChRs (alpha7-nAChRs) are abundant on interneuron dendrites of rats. Moreover, dendritic
Ca2+ transients induced by activation of alpha7-nAChRs increase as a function of distance
from soma. The activation of these extrasynaptic alpha7-nAChRs by cholinergic agonists
either facilitated or depressed backpropagating action potentials, depending on the
timing of alpha7-nAChR activation. We have previously shown that dendritic alpha7-nAChRs
are involved in the regulation of synaptic transmission, suggesting that alpha7-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 alpha7-nAChRs. Our results suggest a new mechanism for a cholinergic
switch in memory encoding and retrieval.
