Nineteen healthy male volunteers participated in a double-blind, six-way, crossover study. With a separation of 1 week between sessions, volunteers received randomly one oral dose of each of the following compounds: 3 or 10 mg of the dopamine (DA2) receptor antagonist and serotonin (5HT1A) agonist DU 29894, 1 mg flesinoxan, 400 mg sulpiride, 3 mg haloperidol or placebo. 2. To assess the dopamine (DA2) antagonistic activity of the different compounds, plasma levels of prolactin were assessed at pre-dose, 0.5, 1, 2, 3, 4, 6 and 24 h post-dose. To assess the serotonin (5HT1A) agonistic activity, plasma levels of ACTH, cortisol and growth hormone were assessed at the same time-points as well as body temperature; the latter was also assessed 8 h post-dose. Plasma levels of DU 29894 were assessed at pre-dose and 2, 3, 4 and 24 h post-dose. 3. Sulpiride, haloperidol and both doses of 3 mg and 10 mg DU 29894 produced statistically significant increases in prolactin levels. The increase produced by 3 mg was roughly equivalent to that produced by 3 mg haloperidol whereas the increase produced by 10 mg DU 29894 was significantly larger. 4. Only 10 mg DU 29894 and 1 mg flesinoxan produced statistically significant increases in ACTH, cortisol and growth hormone. All compounds either showed a significant attenuation of the normal day time increase of body temperature (3 mg DU 29894, haloperidol and sulpiride) or a true significant decrease in body temperature (10 mg DU 29894 and flesinoxan).(ABSTRACT TRUNCATED AT 250 WORDS)
