Expression of Human Insulin-Like Growth Factor Binding Protein ( IGFBP )-4 , 5 , 6 mRNA and Immunohistochemical Localization of IGFBP-4 in Human Fallopian Tube

Choi, D S; Lee, J Y

Abstract

The fallopian tube is a dynamic structure where the epithelium undergoes sex steroid hormone-dependent specific changes and in which gamete transport, maturation, fertilization, and early embryo development and transport occur. In IGF system of the fallopian tube, it is postulated that IGF acts as a mediator of the sex steroid hormone. To confirm the mRNA expressions of IGFBP-4, 5, 6 in the fallopian tube and elucidate the site and menstrual cycle dependency, the relative amounts of mRNA in isthmus, ampulla, and infundibulum of the fallopian tube were measured at different menstrual cycle phases. Also, to differentiate the localization of IGFBP-4 expression in the fallopian tube, immunohistochemical staining was performed using rabbit hIGFBP-4 polyclonal antibody. The results obtained were as follows; Relative amounts of IGFBP-4 mRNA were higher in the infundibulum than those in the other portions of fallopian tube at luteal phase (p<0.05) and showed an increasing tendency from follicular to luteal phase. However, it did not show statistical significance.IGFBP-5 mRNA expression showed menstrual cycle-dependent variations in the order of relative amount of mRNA within the fallopian tube, but showed no statistical difference. Relative amounts of IGFBP-5 mRNA showed an increasing tendency from follicular to luteal phase without statistical significance. Relative amounts of IGFBP-6 mRNA in infundibulum were higher than those in the other sites of fallopian tube without statistical significance and showed no significant menstrual cycle-dependent variations. Unlike IGFBP-4 and 5 mRNA, relative amounts of IGFBP-6 mRNA showed a decreasing tendency from follicular to luteal phase without statistical significance. Immunohistochemical staining of IGFBP-4 in fallopian tubes showed epithelial cells as the primary sites of IGFBP-4 expression and expressions of IGFBP-4 in the ampulla and infundibulum were higher than that in the isthmic area, especially at follicular phase (p<0.05). In conclusion; IGFBP-4, 5, 6 mRNA are expressed in the human fallopian tube; By the fact that IGFBP-4 mRNA shows the site-dependent differences, they may modulate the actions of IGF by changing their expressions according to the intrafallopian site and/or the menstrual cycle phase. Discrepancies between IGFBP-4 mRNA and IGFBP-4 expressions suggest the existence of local regulatory factor in the fallopian tube.