The effect of L-dopa and chlorpromazine on prolactin and growth hormone secretion in normal women.

The time course of simultaneous changes in prolactin (PRL) and growth hormone secretion in response to a single dose of L-dopa and chlorpromazine was determined in normal women. L-Dopa induced greater, but shorter (30 minutes), growth hormone release than concomitant suppression of PRL secretion. The PRL peak following chlorpromazine occurred at the same time as the nadir of PRL after L-dopa (3.5 hours). The quantity of PRL release inhibited by L-dopa equaled the amount of PRL secretion during the period of rebound, suggesting L-dopa inhibits PRL release, but not synthesis, by the pituitary.