Arginine vasopressin potentiates inspiratory bursting in hypoglossal motoneurons of neonatal mice.

Vasopressin (AVP) acts as a neurotransmitter and its activity can potentiate respiratory activity. Hypoglossal (XII) motoneurons that innervate the tongue express V1a vasopressin receptors, which are excitatory. Therefore, we hypothesized that V1a receptor activation at XII motoneurons would potentiate inspiratory bursting. We developed this study to determine whether AVP can potentiate inspiratory bursting in rhythmic medullary slice preparations in neonatal (postnatal, P0-5) mice. Bath or local application of AVP potentiated inspiratory bursting compared to baseline XII inspiratory burst amplitude. Antagonizing V1a receptors revealed significant attenuation of the AVP-mediated potentiation of inspiratory bursting, while antagonism of oxytocin receptors (at which AVP has similar binding affinity) revealed a trend to attenuate AVP-mediated potentiation of inspiratory bursting. Finally, we discovered that the AVP-mediated potentiation of inspiratory bursting increases significantly with postnatal maturation from P0-5. Overall, these data support that AVP potentiates inspiratory bursting directly at XII motoneurons.