Diseases of the Adrenal Cortex

Prolactin modifies the effect of aldosterone on the renal tubules. In the absence of prolactin (and of growth hormone and oxytocin) aldosterone promotes sodium loss: prolactin restores the sodium-retaining effect of aldosterone. The effect does not appear to be of the “all-or-nothing” variety and the renal action of aldosterone may be increased or reduced by altering the prolactin concentration. The effects of prolactin on aldosterone secretion or of aldosterone on prolactin secretion have not been explored.

In the absence of adrenal steroids prolactin secretion rises: it is possible that lack of either mineralocorticoids or glucocorticoids may have this result but there is no clear evidence on this point. Elevated levels of glucocorticoids can suppress prolactin secretion. It is probable that elevated mineralocorticoid levels can do so also although whether directly or via the intermediary of sodium metabolism is unknown.

Prolactin may act on the adrenals to provide a precursor pool on which other agents such as ACTH and angiotensin may act. It may also have a particular effect in stimulating adrenal androgen secretion. The nocturnal prolactin secretion could help to provide precursors for the morning cortisol surge.