Axonal trafficking of an antisense RNA transcribed from a pseudogene is regulated by classical conditioning.

Natural antisense transcripts (NATs) are endogenous RNA molecules that are complementary to known RNA transcripts. The functional significance of NATs is poorly understood, but their prevalence in the CNS suggests a role in brain function. Here we investigated a long NAT (antiNOS-2 RNA) associated with the regulation of nitric oxide (NO) production in the CNS of Lymnaea, an established model for molecular analysis of learning and memory. We show the antiNOS-2 RNA is axonally trafficked and demonstrate that this is regulated by classical conditioning. Critically, a single conditioning trial changes the amount of antiNOS-2 RNA transported along the axon. This occurs within the critical time window when neurotransmitter NO is required for memory formation. Our data suggest a role for the antiNOS-2 RNA in establishing memories through the regulation of NO signaling at the synapse.