Pituitary adrenocortical unresponsiveness in lactate-induced panic

The hypothalamic-pituitary adrenal (HPA) axis responds to a variety of physical and emotional stimuli with increased output of adrenocorticotropic hormone (ACTH) and cortisol, yet there is little known about the activity of this system during episodes of severe anxiety in patients with DSM-III-defined anxiety disorders. To explore further whether alterations of the HPA axis occur during various anxiety states, we measured ACTH and cortisol during lactate infusion in patients with panic disorder and agoraphobia. In eight patients who panicked during lactate infusion, there were no elevations in either ACTH or cortisol. Further, the patterns of hormone secretion did not differ among patients who panicked, nonpanicking patients, or controls. This negative result suggests that the neurobiological mechanisms that mediate panic differ from those responsible for other fear responses.