Assessment of noradrenergic functioning in patients with noncombat-related posttraumatic stress disorder: a study with desmethylimipramine and orthostatic challenges

Abstract

The functioning of the noradrenergic system was assessed in 16 patients with non-combat-related posttraumatic stress disorder (PTSD) and the same number of age- and sex-matched healthy subjects by measuring 1. (1) plasma norepinephrine (NE) levels in supine and upright postures, and 2. (2) growth hormone (GH) responses to challenge with desmethylimipramine (DMI), a NE reuptake inhibitor. Subjects were cannulated at 08:30 h after an overnight fast. Blood samples were drawn for NE levels with subjects in a supine position and after 5 min of standing. After subjects were allowed to rest for 30 min in a supine position, a blood sample was drawn for basal GH (T −15) levels. The second baseline sample was drawn 15 min later (T 0), at which time DMI (1 mg/kg) was given orally, and further blood samples were drawn at 90, 120, and 180 min. PTSD patients had significantly higher baseline NE levels and blunted NE responsivity to postural challenge compared with normal subjects. Basal and DMI-induced GH levels, on the other hand, did not differ in PTSD versus normal subjects. Overall, these findings suggest that non-combat-related PTSD patients have peripheral noradrenergic dysregulation, but central postsynaptic α 2-adrenergic receptor sensitivity is not altered in this patient population.