Neuroendocrine tests during treatment with neuroleptic drugs. III. Plasma growth hormone and prolactin responses to apomorphine.

Hormonal responses to apomorphine 0.005 and/or 0.01 mg/kg body weight were studied in 17 schizophrenic patients during their routine treatment with neuroleptic drugs. Plasma growth hormone (GH) rose in 9 of the 20 tests and in 4 of these GH peak exceeded 5 ng/ml. This preserved GH response to apomorphine was significantly but weakly associated with lower daily doses of neuroleptics. It was unrelated to the extrapyramidal side-effects, plasma prolactin (PRL) level, duration of treatment or its therapeutic effect. In 13 of the 20 tests, plasma PRL declined by more than 20 per cent of the baseline level. This was similar to the fall in PRL observed after placebo in the group studied previously. The absolute decline in plasma PRL following apomorphine correlated positively with the baseline PRL concentration and was unrelated to the daily doses of neuroleptics or to any other variable considered.