Further studies of the putative serotonin agonist, m-chlorophenylpiperazine: evidence for a serotonin receptor mediated mechanism of action in humans.

To further evaluate the effects and mechanism of action of the putative serotonin agonist m-chlorophenylpiperazine (m-CPP) in humans, changes in plasma prolactin, cortisol, growth hormone, ACTH and body temperature were studied in a group of 10 healthy volunteers following oral administration of m-CPP (0.75 mg/kg), before and after pretreatment with the serotonin receptor antagonist metergoline (MTG). M-CPP produced transient significant increases in plasma prolactin, cortisol, ACTH and in body temperature, but did not significantly alter plasma growth hormone concentration. Moreover, pretreatment with the 5HT antagonist metergoline blocked the m-CPP-induced hormonal and temperature changes. These findings provide strong support for m-CPP's effects in humans being mediated through an interaction with 5HT receptors, and thus support the usefulness of m-CPP as a pharmacologic tool for studying disease and drug-induced alterations in serotonin function in man.