PTK7 and panic disorder: An example for such an altered equilibrium of steroid composition is the prominent decline in 3α-reduced neurosteroids after challenge with sodium lactate or cholecystokinin tetrapeptide (CCK-4) in patients with panic disorder together with a marked increase in the 3β-reduced isomer (Ströhle et al., 2003), which may result in a decreased GABAergic tone related to pathophysiology of panic attacks.