Effects of CCK-4 infusion on the acoustic eye-blink startle and psychophysiological measures in healthy volunteers

The acoustic startle response (ASR) and a range of psychophysiological para meters were evaluated during a continuous intravenous administration of cho lecystokinin-tetrapeptide (CCK-4) in healthy volunteers. Subjects (n=28) we re randomly assigned to double-blind infusion of either CCK-4 (0.5 mg/60 mi n) or placebo. The ASR sessions were performed prior to infusion and at 20 min and 50 min after the onset of infusion by recording eye-blink response to a series of acoustic stimuli (110 dB, 40 ms). An effect of CCK-4 on the eye-blink startle was observed in the first half of infusion. CCK-4 produce d an increase of eye-blink startle amplitude from baseline values in contra st to the decrease observed at this time point with placebo. A mild increas e in anxiety and heart rate followed by fatigue was reported with CCK-4. Ad ministration of CCK-4 produced increases in plasma concentrations of adreno corticotropic hormone, cortisol, prolactin and growth hormone. The results of this study show that a prolonged intravenous administration of CCK-4 may be a useful challenge method for further studies on the role of CCK system in the modulation of human anxiety and stress response.