Human fallopian tube as an extraovarian source of relaxin: messenger ribonucleic acid expression and cellular localization of immunoreactive protein and 125I-relaxin binding sites.

By means of specific human relaxin primers that originated from relaxin A and B chains, a monoclonal antibody, and 125I-relaxin, the expression of mRNA and immunoreactive protein and the presence of binding sites for relaxin were investigated in human fallopian tubes. Reverse transcription polymerase chain reaction (RT-PCR) analysis of total RNA isolated from tubal tissues revealed the predicted 434-bp fragments originating from both the H1 and H2 relaxin genes. Restriction enzyme digestion of the RT-PCR products with Msp I (Hpa II), present only in the relaxin H1 sequence, resulted in the anticipated 175- and 259-bp fragments, whereas digestion with Hpa I, which is present in the relaxin H2 sequence and should have resulted in 188- and 246-bp fragments, induced a limited and partial digestion of the product. Codigestion of the RT-PCR product with Msp I+Hpa I also resulted in 175- and 259-bp fragments. The immunoreactive relaxin protein was present primarily in the tubal epithelial cells of the ampullary and isthmus regions, and with weaker intensity in tubal smooth muscle cells. Immunoreactive relaxin either was barely present or was absent in other tubal cell types. The intensity of immunostaining for relaxin in the epithelial cells appeared not to be cycle-dependent; however, these cells showed a lower immunostaining at the late secretory phase of the menstrual cycle than at other reproductive stages and an absence of immunostaining during the postmenopausal period.(ABSTRACT TRUNCATED AT 250 WORDS)