Identification, purification, and partial characterization of a factor from rabbit serum that inhibits prolactin secretion by pituitary cells cultured in vitro.

A biological factor that inhibited prolactin secretion by pituitary cells cultured in vitro was identified, purified, and partially characterized from normal rabbit serum. This biological factor was also found to potentiate dopamine-mediated aortic contraction using rabbit aortic strips in vitro. Following SDS-PAGE, this factor displayed an apparent Mr of 17 kDa, which is different from the Mr of most known endogenous factors having an inhibiting activity on pituitary prolactin secretion, suggesting that this may be a yet-to-be identified novel molecule.