Electrical signaling in central orexin/hypo cretin circuits: Tuning arousal and appetite to fit the environment

In mammals, alertness and foraging are linked to the light-dark cycle and body energy levels. This link is crucially dependent on the novel peptide transmitters orexins/hypocretins. The firing of orexin neurons encodes the overall internal (body energy levels) and external (time of day) environment. In turn, orexins modulate arousal and appetite by innervating and electrically exciting wake- and appetite-promoting neurons. Electrical signaling in orexin circuits thereby couples arousal to the environment and synchronizes foraging with states of high alertness.