Prolactin molecular heterogeneity. Response to thyrotropin-releasing hormone stimulation of concanavalin A-bound and -unbound immunoassayable prolactin during human pregnancy.
Since the milieu of pregnancy stimulates physiologic hyperprolactinemia, we questioned whether prolactin secreted during normal pregnancy contains a large-molecular weight component that binds to concanavalin A and whether this large-molecular weight prolactin contributes to the thyrotropin-releasing hormone (TRH)-releasable pool. Serum was collected from pregnant patients (n = 28) undergoing TRH stimulation tests. This serum was passed through a concanavalin A column and eluted with 0.2M alpha-methylmannoside. Concanavalin A-bound prolactin, as determined by radioimmunoassay, ranged from 10% to 30% of the total immunoassayable prolactin. An increase in the basal serum concentration of both concanavalin A-bound and -unbound prolactin occurred as pregnancy progressed. However, throughout gestation, only the concanavalin A-unbound prolactin increased after TRH stimulation. The concanavalin A-bound prolactin was found to have a molecular weight of 60,000 by means of Sephadex G-100 permeation chromatography.
D003208:Concanavalin A / Q000378:metabolism*; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008970:Molecular Weight; D011247:Pregnancy; D011388:Prolactin / Q000097:blood / Q000302:isolation & purification* / Q000378:metabolism; D011863:Radioimmunoassay; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D013997:Time Factors
D003208:Concanavalin A; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin