Hormonal responses to meta-chlorophenylpiperazine (m-CPP) are undiminished by acute m-CPP pretreatment PSYCHIATRY RESEARCH Psychiatry Research 62 (1996) 139-145 Emil F. Coccaro*a, Richard J. Kavoussia, Robert L. Trestmanbl”, Steven M. Gabrielb, Thomas B. Cooperd, Larry J. Sieverb” zyxwvutsrqponmlkjihgfe aDepartment of Psychiatry, Medical College of Pennsylvania and Hahnemann University, EPPI, 3200 Henry Avenue. Philadelphia, PA 19129. USA bDepartment of Psychiatry, Mt. Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA ‘Psychiatry Service. IIbA. Bronx DVA Medical Center, I30 W . Kingsbridge Road, Bronx, NY 10468, USA ‘Analytic Psychopharmacology Laboratory, Nathan Kline Institute, Orangeburg, NY 10962, USA Received 13 April 1995; revised 28 December 1995; accepted 2 February 1996 zyxwvutsrqponmlkjihgfedcbaZY Abstract Two challenges with meta-chlorophenylpiperazine (m-CPP, 0.5 mgkg, p.o.) were performed in healthy volunteers to test the short-term stability of hormonal responses. Challenges were performed in an identical fashion and were con- ducted on sequential days. Circulating m-CPP plasma levels, as well as prolactin and cortisol responses to m-CPP, were correspondingly similar in magnitude on the 2 days. These data suggest that both prolactin and cortisol responses to single oral administrations of m-CPP are stable over at least a 24-h period. Keywords: Serotonin; Prolactin; Cortisol 1. Introduction Hormonal responses to neuropharmacological probes have been used to assess central receptor responsivity in human subjects for more than a decade. To date, a variety of studies have demonstrated altered hormonal responses to phar- macological challenge in psychiatric compared with nonpsychiatric subjects. These data have been interpreted as suggesting that the responsivi- ty of central neurotransmitter receptors is reduced l Corresponding author, Tel: + I 2 I5 8424208; Fax: + I 215 842-4321. (or enhanced) in individuals meeting criteria for certain psychiatric disorders and that abnormali- ties in neurotransmitter systems play a role in the pathophysiology of the disorders (Coccaro and Kavoussi, 1994). While several methodological issues regarding the neuroendocrine response to pharmacological challenge studies have been addressed, the test- retest reliability of various probes has, until recently, received little attention. In addition, there is only limited information about the effect of prior exposure to a pharmacologic probe on subsequent challenge with the same probe. This issue is important because repeated studies with 0165-1781/96/%15.00 0 1996 Elsevier Science Ireland Ltd. All rights reserved PII: SO165-1781(96)02826-O