Presynaptic type III neuregulin 1 is required for sustained enhancement of hippocampal transmission by nicotine and for axonal targeting of α7 nicotinic acetylcholine receptors

Both the neuregulin 1 (Nrg1) and alpha 7 nicotinic acetylcholine receptor (alpha 7*nAChRs) genes have been linked to schizophrenia and associated sensory-motor gating deficits. The prominence of nicotine addiction in schizophrenic patients is reflected in the normalization of gating deficits by nicotine self-administration. To assess the role of presynaptic type III Nrg1 at hippocampal-accumbens synapses, an important relay in sensory-motor gating, we developed a specialized preparation of chimeric circuits in vitro. Synaptic relays from Nrg1(tm1Lwr) heterozygote ventral hippocampal slices to wild-type (WT) nucleus accumbens neurons ( 1) lack a sustained, alpha 7*nAChRs-mediated phase of synaptic potentiation seen in comparable WT/WT circuits and ( 2) are deficient in targeting alpha 7*nAChRs to presynaptic sites. Thus, selective alteration of the level of presynaptic type III Nrg1 dramatically affects the modulation of glutamatergic transmission at ventral hippocampal to nucleus accumbens synapses.