SUSTAINED ELEVATION OF VASOPRESSIN PLASMA-LEVELS IN HEALTHY-YOUNG MEN, BUT NOT IN ABSTINENT ALCOHOLICS, UPON EXPECTATION OF NOVELTY

The role of vasopressin (AVP) as a stress hormone in man is still a ma tter of controversy. Thus, the response of plasma AVP, among other hor mones, to either intravenously injected human corticotropin releasing factor (hCRF, in the absence or presence of the opioid antagonist nalo xone) or a combined 5-minute stress test was compared in healthy men ( n = 10) and short-term abstinent alcoholics (n = 11), a group with rec ognized abnormalities of humoral stress parameters. Stimuli were appli ed blindly and in random order, one per day, in a 3-day experimental b lock. A second block using the same standardized protocol was carried out 12 weeks later. Alcoholics entered block I 8 days after the last e thanol ingestion. Up to block II, they were strictly controlled for ab stinence. On each experimental day, subjects remained supine from 0700 h until 1500h. Stimuli were applied alternatively at 1030h each day. F ourteen blood samples were drawn per day with simultaneous fluid subst itution. There were no significant changes in plasma AVP as an acute r esponse to any of the stimuli in either group or block. However, unexp ectedly, controls had significantly higher basal AVP levels throughout block I as compared with block II without concomitant changes in plas ma osmolality or blood pressure. Further analysis of the data revealed that the dramatically increased AVP levels of the five younger contro l subjects accounted for this difference. In fact, AVP levels in the f ive older healthy subjects and in all alcoholics remained low througho ut the two blocks. Our data suggest that plasma AVP is continuously el evated in healthy young men upon anticipation of novelty. In contrast, healthy men of the older age group and early abstinent alcoholics see m to lack such a sustained AVP response. (C) 1997 Elsevier Science Ltd .