Tubero-infundibular dopaminergic function in cirrhotic patients: evaluation by nomifensine and domperidone

Cirrhotic patients reportedly show alterations of anterior pituitary hormone secretion, which may reflect an underlying defective central neurotransmitter function. In this study, we have investigated the catecholaminergic control of prolactin (Prl) and growth hormone (GH) secretion in cirrhotic patients by means of an indirectly acting dopamine (DA) and norepinephrine agonist, nomifensine (Nom), and a DA receptor antagonist, domperidone (Dom). Basal GH levels were higher in the 12 female and male cirrhotic patients than in the 12 age- and sex-matched normal controls, while no difference was present in basal Prl values. Administration of Nom (200 mg po) suppressed basal Prl levels (at least 30% inhibition at three consecutive times post-drug administration) in 6/12 controls and in 6/12 cirrhotic patients, the frequency of negative responses not being different between the two groups. Nom induced a slight elevation of GH levels in controls, and evoked a more marked and sustained GH increase in cirrhotic patients. Administration of Dom (4 mg iv) induced similar Prl increments in 6 male controls and 6 male cirrhotic patients. Normal Prl responsiveness to Nom and Dom points to the existence of preserved tubero-infundibular DA function and modulation of pituitary DA receptors in the cirrhotic patients investigated. Higher GH responsiveness to Nom is compatible with a different bioavailability of the drug.