Localization and quantification of insulin-like growth factor-I (IGF-I) and IGF-II/mannose-6-phosphate (IGF-II/M6P) receptors in pig embryos during early pregnancy.
To assess a potential role of insulin-like growth factor-I (IGF-I) and -II (IGF-II) in early embryonic development, the presence of their receptors was investigated by both immunohistochemistry and autoradiography experiments on whole embryos at Days 4 and 6 of pregnancy, on embryo sections at Days 8 and 10, and on placenta at Day 20 of pregnancy. Immunohistochemistry experiments were performed by using specific polyclonal antibodies raised against human IGF-I and IGF-II/mannose-6-phosphate (IGF-II/M6P) receptors. By autoradiography, specificity of [125I]-IGF-I and [125I]-IGF-II binding on embryonic cells was assessed by competition with unlabeled IGF-I and IGF-II, and quantification of the autoradiographic signal was performed by image analysis. The presence of IGF-I receptors on porcine trophectoderm cells was detected neither by immunohistochemistry nor by autoradioradiography on whole embryos or embryo sections. IGF-I receptors were present in the placenta at Day 20 of pregnancy, but only on endometrial cells. In contrast, IGF-II/M6P receptors were detected on porcine trophectoderm cells by both immunohistochemistry and autoradiography on whole embryos, on embryo sections at Day 8 and Day 10 of pregnancy, and on fetal and maternal compartments of the placenta at Day 20. The number of IGF-II/M6P receptors on trophectoderm cells was greatly heterogeneous between embryos within the same litters. There was no relationship between the number of IGF-II/M6P receptors on trophectoderm cells and the age or size of embryos between Day 8 and Day 10 of pregnancy. The involvement of the IGF-II/M6P receptor in early embryonic development in the pig remains to be determined.
Chastant
S
S
Station INRA de Physiologie de la Reproduction des Mammifères Domestiques URA CNRS 1291, Nouzilly, France.
Monget
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P
Terqui
M
M
D000818:Animals; D001345:Autoradiography; D001667:Binding, Competitive; D005260:Female; D005865:Gestational Age; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D007457:Iodine Radioisotopes; D010920:Placenta / Q000737:chemistry / Q000378:metabolism; D011247:Pregnancy; D017526:Receptor, IGF Type 1 / Q000032:analysis* / Q000378:metabolism; D017527:Receptor, IGF Type 2 / Q000032:analysis* / Q000378:metabolism; D013552:Swine / Q000196:embryology*; D014327:Trophoblasts / Q000737:chemistry / Q000378:metabolism
D007457:Iodine Radioisotopes; D017527:Receptor, IGF Type 2; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D017526:Receptor, IGF Type 1