Pentagastrin test for anxiety--psychophysiology and personality.

Rationale: CCK(B) receptor agonists such as pentagastrin or CCK(4) have anxiogenic panic-like effects in humans. Our previous findings are in agreement with a relationship between C-peptide plasma levels (as a measure of insulin release) and sensitivity to psychotropic activation by CCK(B) receptor stimulation.

Objectives: Our present aim was to study the transient humoral, physiological and psychotropic effects of pentagastrin bolus injection and whether personality might affect the outcome.

Methods: Pentagastrin was given in bolus i.v. injections to healthy volunteers at increasing doses (0.003, 0.012, 0.05 and 0.2 microg/kg). Physiological parameters were recorded before and during each pentagastrin challenge and humoral variables described previously were included in the analyzes. Subjects rated the discomfort following pentagastrin administration on the state anxiety and discomfort scale (SADS). The Karolinska scale of personality (KSP), anxiety sensitivity index (ASI) and Hamilton anxiety scale (HAS) were used to characterize the subjects before the test.

Results: Galvanic skin response (GSR) and heart rate (HR) were significantly increased within 1 min following 0.2 microg/kg pentagastrin, the GSR increase correlating negatively to the C-peptide increase and positively to ratings on SADS. Even the lower dose (0.05 microg/kg pentagastrin) induced a significant increase in GSR. ASI measures correlated weakly to the increase in ratings on SADS following 0.05 microg/kg and 0.2 microg/kg pentagastrin.

Conclusions: We found correlations between psychophysiology, humoral response and subjective ratings following pentagastrin administration. CCK(B) receptor stimulation might reveal phenotype properties predictive of anxiety-related traits, measurable through serum levels of C-peptide. Furthermore, our results support the predictive value of ASI for fearfulness.