Orexin links emotional stress to autonomic functions

We studied autonomic functions in orexin-deficient mice and found abnormalities in the emotional state-dependent adjustment of the central autonomic regulation on circulation and respiration. These are summarized as follows. 1) Orexin-deficient mice exposed to a stressor exhibited an attenuated fight-or-flight response, including increases in respiration and blood pressure and stress-induced analgesia. 2) Stimulation to the amygdala (AMG) or the bed nucleus of the stria terminalis (BNST), both of which are implicated in the stress-induced autonomic responses, induced long-lasting cardiorespiratory excitation in wild-type mice but not in the orexin neuron-ablated mice. Hence, it is likely that the orexin system is one of the essential modulators required for orchestrating the neural circuits controlling autonomic functions and emotional behaviors. (C) 2010 Elsevier B.V. All rights reserved.