[Prolactin releasing activity in serum of pregnant women and patients with galactorrhea-amenorrhea syndrome].

Serum samples obtained from 18 normal men and women, 24 pregnant women of the third trimester, and 8 patients with galactorrhea-amenorrhea syndrome (GAS) were subjected to a 3-phase methanol extraction. The serum extract released prolactin (PRL) specifically from rat anterior pituitary in vitro. The PRL releasing activity (PRA) was dependent on the incubation time and dose of serum extract, while independent on TRH or PRL in serum. The mean PRA in serum of pregnant women was significantly (p less than 0.02) higher than one of normal subjects. The mean PRA in serum of GAS was significantly higher than in pregnant women (p less than 0.05), and in normal subjects (p less than 0.001). When the individual PRL levels were compared to the PRA in samples from pregnant women and normal subjects, a significant (p less than 0.02) positive correlation evolved. These results indicate that a PRL releasing substance(s) distinct from TRH is (are) present in serum, and has (have) a relationship to the PRL concentration and late pregnant states.