Orexin enhances firing activities in the gigantocellular reticular nucleus through the activation of non-selective cationic conductance.

•Orexin enhances the firing activities of Gi neurons.•A postsynaptic depolarization contributes to orexin-enhanced firings in Gi neurons.•Orexin also shortens the inter-spike intervals of firings evoked in Gi neurons.•The activation of non-selective cationic conductance underlies the orexin's actions.