Evidence for the synthesis of corticosteroid-binding globulin in human placenta

We demonstrated the expression of corticosteroid-binding globulin (CBG) in human placenta using reverse transcription-polymerase chain reaction-Southe rn blot analysis and immunohistochemical and immunoblotting studies, In the RT-PCR-Southern blot analysis, only one predicted PCR product was detected without nonspecific products in all samples of human placenta and 3A (tPA- 30-1) human placental cells, In Western blot analysis, polyclonal anti-CBG antibodies recognized a protein of approximately 55 kD in the protein extra cts prepared from 3A (tPA-30-1) cells, Additionally, CBG mRNA expression wa s demonstrated by in situ hybridization in the syncytiotrophoblasts. Immuno histochemical studies performed on the placenta demonstrated the presence o f specific immunoreactivity in the syncytiotrophoblast layer surrounding th e chorionic villi, These findings suggest that CBG is synthesized in human placenta during pregnancy in addition to its synthesis in the liver.