Stimulatory control of prolactin by dopamine

1. In addition to evidence that dopamine (DA) inhibits prolactin (PRL) via the tuberinfundibular system, there is also evidence for excitatory effects of DA via that system as well as evidence for regulation by DA sites lying behind the blood brain barrier. 2. Apomorphine (APO) was given to rats pretreated with either a peripheral (domperidone, DOM) or a central (haloperidol, HAL) DA blocker and prolactin responses examined. 3. Both DOM and HAL caused prolactin elevation. 4. Further elevation of prolactin was produced by APO in HAL treated animals, indicating an excitatory dopamine effect on prolactin.