Peptide-signaling and miRNA regulation of transmitter switching affecting social preference

Sensory circuit activation can induce neurotransmitter respecification. To understand the consequences and mechanisms of this neuroplasticity we investigated the effects of olfactory system activation on transmitter expression in interneurons of the accessory olfactory bulb (AOB) during development. Frog larvae use olfactory-mediated kin recognition to distinguish siblings from non-siblings. Prolonged exposure to kin (sibling) or non-kin (non-sibling) odorants changed the number of neurons expressing dopamine or GABA compared to odorant deprivation (orphan condition). To identify signaling molecules mediating this behavior we performed mass spectrometry of kin-conditioned water samples. Vitellogenin-derived peptides, uniquely present in kin-conditioned samples of one genotype, were sufficient to elicit aversion behavior in non-kin larvae. RNA profiling identified AOB microRNAs (miRs) differentially regulated across conditions. Inhibition of miR-375 and miR-200b revealed that they regulate the dopaminergic and GABAergic phenotypes by targeting Pax6 and Bcl11b. Altering the ratio of dopamine/GABA AOB interneurons or locally introducing receptor blockers reversed kinship preference. The AOBs of 15 larvae (stage 45) raised in sibling, orphan, or non-sibling conditions were frozen, cryosectioned at 50 μm and neuronal tissue was harvested with scalpels for clean dissection. Total RNA was extracted from tissue with the “Recover All Total Nucleic Acid” isolation kit. RNA quality was assessed on a Bioanalyzer and degraded samples excluded from RNA sequencing. Library preparation and RNA sequencing were performed at the UCSD Biogem core.