PROLACTIN AND ADRENAL ANDROGEN SECRETION

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Abstract
The aim of this study was to investigate the role of prolactin in the secretion by the adrenal of dehydroepiandrosterone (DHA) and its sulphate (DHA‐S). Therefore prolactin and DHA‐S levels were determined in different groups of subjects under various physiological and pathological conditions. In patients with prolactinomas, or with pharmacologically induced hyperprolactinaemia, plasma DHA‐S and, to lesser extend, DHA concentrations were elevated, and the DHA‐S blood production rate greatly increased. ACTH stimulation which did not influence DHA‐S concentrations in normals, caused a significant increase in patients with prolactinomas; the increase in DHA concentrations was similar in normal subjects and in prolactinoma patients. Bromocriptine treatment of prolactinaemia patients normalized both prolactin and DHA‐S concentrations. Acute elevation of prolactin in normal subjects by TRH stimulation or by short term administration of sulpiride, in contrast to long term treatment, did not influence DHA‐S levels. During pregnancy, notwithstanding high prolactin concentrations, DHA‐S concentrations were lower than during the menstrual cycle. In patients with prolactinomas, given glucocorticoid replacement with cortisol, DHA‐S concentrations were low (normal) notwithstanding persistently high prolactin concentrations. It is concluded that only prolonged elevation of prolactin induces increased DHA‐S secretion by the adrenal cortex and that normal ACTH secretion is a prerequisite for this effect. The absence of elevated DHA‐S concentrations in pregnancy might be explained by the rapid rate of metabolism, as the DHA‐S production rate is increased. The intimate mechanism of prolactin and ACTH interaction at the adrenal cortex remains however unknown.