Clinical endocrinology
-
Clinical endocrinology · Jan 1984
Dopaminergic control of gonadotrophin secretion in normal women and in patients with pathological hyperprolactinaemia.
The role of dopaminergic mechanisms in the control of gonadotrophin secretion in normal and hyperprolactinaemic subjects is controversial. Whilst bromocriptine, a potent dopamine agonist, has been used to restore normal gonadotrophin secretion in subjects with pathological hyperprolactinaemia (PHP), dopamine and dopamine agonists have been reported to suppress basal and stimulated gonadotrophin release. We therefore investigated the importance of dopaminergic control of gonadotrophin secretion by studying LH, FSH and PRL responses in normal and PHP subjects to central dopamine synthesis inhibition using monoiodotyrosine (MIT) and to a 4 h dopamine infusion designed to elevate peripheral plasma dopamine concentration to levels reported for pituitary portal plasma (1-6 ng/ml). ⋯ We conclude that dopamine mechanisms do not play a significant role in modulating gonadotrophin release in normal subjects. In PHP patients, PRL feedback results in increased hypothalamic dopamine activity which in turn inhibits LH release. We conclude that the inhibitory action of dopamine on PRL release restores LH secretion by removing central dopaminergic inhibition through hypothalamic feedback of PRL.