Neurohormonal responses to cholecystokinin tetrapeptide: a comparison of younger and older healthy subjects

We recently found that, compared with younger healthy subjects, older healt hy subjects had less symptomatic and cardiovascular response to the panicog enic agent cholecystokinin tetrapeptide (CCK-4). As an exploratory part of that study, we also evaluated the effect of aging on neurohormonal response s to CCK-4. These hormonal data are the focus of this article. Forty health y volunteers aged 20-35 years and 40 healthy volunteers aged 65-81 years, d ivided equally between men and women, were compared on their hormonal respo nses (maximum change from baseline in growth hormone [GH], prolactin, adren ocorticotropic hormone [ACTH], and cortisol) to the intravenous administrat ion of 50 mu g of CCK-4 or placebo. Blood samples for serum hormone determi nation were collected at 2 minutes prior to the intravenous challenge (base line) and at 2, 5, and 10 minutes after the challenge. In both age groups, maximum increase in prolactin, ACTH and cortisol was significantly greater with CCK-4 than with placebo. Following administration of CCK-4, younger an d older groups did not significantly differ in maximum increase in prolacti n, ACTH, or cortisol. Older subjects had a statistically significant smalle r increase in GH compared with younger subjects but the magnitude of the di fference was small and of doubtful clinical relevance. Older subjects who h ad a panic attack had significantly greater elevations of all hormones comp ared with those who did not panic and younger panickers had a significantly greater elevation of GH compared with young nonpanickers. For the most par t, maximum changes in hormonal levels were not correlated with symptom seve rity, suggesting that other factors may have contributed to the differentia l effect of panic on the HPA axis. (C) 2000 Elsevier Science Ltd. All right s reserved.