Investigations with the specific mu-opiate receptor agonist fentanyl in depressive patients: growth hormone, prolactin, cortisol, noradrenaline and euphoric responses.

15 depressive patients and 15 controls, 9 of them age- and sex-matched, were administered 0.2 mg/70 kg i.v. fentanyl, a specific and highly potent mu-opiate receptor agonist. Growth hormone response was significantly reduced in depressive patients in comparison to controls, whereas prolactin response did not significantly differ between the two groups. Cortisol plasma concentration increased in depressive patients and decreased in controls. The difference between the groups failed to reach statistical significance. Only in patients, but not in controls, fentanyl led to a significant increase in plasma noradrenaline. In contrast, a significant increase in the visual analogue scale for the evaluation of psychotropic drug effects was found only in controls after fentanyl administration. From these preliminary results in connection with other studies we conclude a possible involvement of a disturbed opioid system at least in a subgroup of depressive patients.