Effects of morphine on serum growth hormone, cortisol, prolactin and thyroid stimulating hormone in man

Morphine administration in man results in a significant increase in serum prolactin without altering the levels of growth hormone, thyroid stimulating hormone and cortisol. Apomorphine prevented the morphine induced prolactin rise. It is suggested that the effect on prolactin is not mediated via non specific stress or changes in the thyroid stimulating hormone releasing factor, but via suppression prolactin inhibiting factor or activation of a specific prolactin releasing factor.