Noradrenergic and dopaminergic interrelation in schizophrenia.

Growth hormone (GH) and prolactin (PRL) responses to the acute administration of clonidine (150 micrograms) and apomorphine (0.5 mg) were investigated in parallel in 20 drug-free subchronic and chronic schizophrenic patients and in nine control subjects. Neither basal levels of the two hormones nor their mean responses to both stimuli differed significantly between the two groups. However, eight patients had blunted GH responses to clonidine and seven to apomorphine; only two patients showed blunted GH responses to both stimuli. The blunted GH response to apomorphine correlated with the chronicity of the disorder. A greater than normal GH response to clonidine stimulation was observed in paranoid patients. Significant correlations were observed between negative symptoms and GH responses to clonidine (negative), between negative symptoms and PRL responses to apomorphine (positive), and between positive symptoms and PRL responses to apomorphine (negative).