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Placental insulin receptors from normal and diabetic pregnancies respond differently to enzymatic treatment
A.13 PLACENTAL INSULIN RECEPTORS FROM NORMAL AND DIABETIC PREGNANCIES RESPOND DIFFERENTLY TO ENZYMATIC TREATMENT Gernot Desoye. Dept. Obstet. Gynecol., Univ. of A-8036 Graz, Austria. The influence of insulin receptor carbohydrates (CHO) and of the membrane lipid composition on insulin binding to syncytiotrophoblast plasma membranes was investigated. Plasma membranes from 9 normal (N), 7 gestational diabetic (CD) and IO overt diabetic (OD) pregnancies were pre-incubated with 2 lectins (ConA, WGA), with various glycosidases, trypsin or phospholipases (PLAse) A2, C, D or with buffer only (controls). Insulin binding was measured by a radioreceptor assay. Maximum binding (MB) was affected by all kinds of treatment with trypsin producing the most pronounced effect (decrease to 30% of controls, ~~0.05) due to a decrease in both, affinity and number of receptors. If the changes in MB relative to controls were compared between N, CD and OD, no differences were detected for the lectins, the CHO specific enzymes and for trypsin. However, the mean MB relative to controls was different in CD as compared to N after treatment with PLAse A2 [lO5+5% (CD) vs 85+14% (N); p
IMMUNOHISTOCHEMICAL EVIDENCE THAT THE MAJORITY OF INSULIN RECEPTORS IN HUMAN TERM PLACENTA IS LOCATED N ENDOTHELI L CELLS. Gernot Desoyel, Mic ele Hartmann’, Astrid laschitz ,Gottfried Dohr $ , Gabrtele I Dept Obst Gynecol, ? Inst Histol .9 Kohnen3 and Peter Kaufma ?h? n Embryo], University of A-8036 Graz, Austria, and Inst Anatomy, RWTH Aachen, D-5100 Aachen, FRG. We investigated the localization of insulin receptors (IR) on cryosections of human non-pathologic 1st trimester and full term placentae by indirect immunohistochemistry with 3 different mabs against the extra- and intracellular domain of the IR, respectively. In term placentae some discontinued areas of the microvillous membrane of the syncytio-trophoblast (ST) were very weekly stained. In contrast, the endothelial cells (EC) of the capillaries in the terminal villi were strongly decorated. The same staining pattern was observed with the EC of all vessel types in mature intermediate and stem villi and in the chorionic plate. In the chorionic plate and in the amniochorion the amniotic epithelium and fibroblasts in the stroma were conspicuously stained. In placentae from 6-10 wks p.m. only trophoblasts were stained. However, in placentae from II-14 wks p.m. EC commenced to react with the antiIR mabs and the trophoblasts were less intensely decorated than in early first trimester placentae. The data indicate: (I) The degree of expression on villous trophoblast decreases and that of EC increases throughout gestation, (2) ST of human term placentae expresses, if any, a very low level of surface IR, and (3) the majority of IR in human term placentae is located in EC. Our results provide evidence of a regulatory role of fetal insulin on placental metabolism in human term placenta and suggest a developmental expression of placenta1 IR.
IMMUNOHISTOCHEMICAL EVIDENCE THAT THE MAJORITY OF INSULIN RECEPTORS IN HUMAN TERM PLACENTA IS LOCATED N ENDOTHELI L CELLS. Gernot Desoyel, Mic ele Hartmann’, Astrid laschitz ,Gottfried Dohr $ , Gabrtele I Dept Obst Gynecol, ? Inst Histol .9 Kohnen3 and Peter Kaufma ?h? n Embryo], University of A-8036 Graz, Austria, and Inst Anatomy, RWTH Aachen, D-5100 Aachen, FRG. We investigated the localization of insulin receptors (IR) on cryosections of human non-pathologic 1st trimester and full term placentae by indirect immunohistochemistry with 3 different mabs against the extra- and intracellular domain of the IR, respectively. In term placentae some discontinued areas of the microvillous membrane of the syncytio-trophoblast (ST) were very weekly stained. In contrast, the endothelial cells (EC) of the capillaries in the terminal villi were strongly decorated. The same staining pattern was observed with the EC of all vessel types in mature intermediate and stem villi and in the chorionic plate. In the chorionic plate and in the amniochorion the amniotic epithelium and fibroblasts in the stroma were conspicuously stained. In placentae from 6-10 wks p.m. only trophoblasts were stained. However, in placentae from II-14 wks p.m. EC commenced to react with the antiIR mabs and the trophoblasts were less intensely decorated than in early first trimester placentae. The data indicate: (I) The degree of expression on villous trophoblast decreases and that of EC increases throughout gestation, (2) ST of human term placentae expresses, if any, a very low level of surface IR, and (3) the majority of IR in human term placentae is located in EC. Our results provide evidence of a regulatory role of fetal insulin on placental metabolism in human term placenta and suggest a developmental expression of placenta1 IR.