Hypoxia facilitates panic-like response induced by electrical stimulation of Dorsal Periaqueductal Gray.

Panic disorder (PD) is a psychiatric syndrome characterized by the occurrence of repeated and unexpected panic attacks (PA). Plenty of evidence suggests that periaqueductal gray matter (PAG) mediates both respiratory (suffocation-like) and non-respiratory (predation-like) types of PA. Previous studies showed that the selective stimulation of peripheral chemoreceptors by i.v. injections of potassium cyanide (KCN) (pharmacological hypoxia) not only produced escape by its own but also facilitated escape responses induced by electrical stimulation of PAG (Neuroscience;200:59, 2012). Although the environmental hypercapnia (HPC) facilitated KCN-evoked escape, it did not produce escape by its own. These results suggest that PAG harbors a suffocation alarm system sensitive to hypoxia (HPX) that may be potentiated by HPC. However, it remained unclear whether the environmental suffocation facilitates escape responses to electrical stimulation of PAG.