Studies of uterine specific glycoproteins during early pregnancy of the rabbitOryctolagus cuniculus

Abstract

Between the 3rd and 6th day post coitum the dry substance of uterine fluid contains nearly 60% peptide chains, on the 6th day 19 h p.c. only 35%. The remaining 40 and 65% resp. consist mainly of carbohydrates (cf. III.1). By means of disc electrophoresis, thin layer chromatography following hydrolysis and molecular sieve chromatography, we were able to characterize 4 uterine specific proteins, 2 of which are carbohydrate rich glycoproteins. Their relative concentrations were determined between 0 and 8 day p.c. (of. III.2): Glycoprotein I can already be found during oestrus. Its concentration increases slightly from the 3rd to the 5th day p.c., more rapidly up to the 6th day 6 h p.c., and decreases later (of.III.2b). The molecular weight is estimated to be around 50,000 (cf.III.4). Postalbumin as well as Uteroglobin can be found shortly after ovulation. Its concentration stays nearly constant between 3rd and 6th day p.c., and decreases during the 6th day p.c. (of.III.2b). Its molecular weight is in the same range as that of Uteroglobin, nearly 30,000 (of.III.4. Uteroglobin is most probably free of carbohydrates. Its concentration increases rapidly between 16 and 40 h p.c., slightly until the 5th day p.c., and decreases later (cf.III.2b). At 6th day p.c. about 50% of the peptide chains of uterine fluid are Uteroglobin (cf.III.2.g). Glycoprotein II is not secreted before the 6th day p.c. It has a comparativly high content of galactose (cf.III.3.d). Its concentration increases rapidly during the 6th day p.c. (cf.III.2.b). The moleculare weight is higher than 70,000 (cf.III. 4).These proteins and glycoproteins have also been found inblastocoelic fluid after the 5th day p.c. (cf.III.2.c).Aftersuperovulation induced by hormones, and natural mating, the pregnancy specific protein pattern is not fully developed (cf.III.2.d). Inpseudopregnancy, triggered by mating with vasectomized males, the same proteins as in normal pregnancy were found from the 6th day 6 h to the 6th day 19 h p.c. If no blastocysts are implanted, the protein pattern of the 6th day 19 h p.c. persists nearly unchanged until the 9th day p.c. (cf.III.2.e).Duringimplantation uterus and blastocyst lumens are filled with serum proteins, which tend to cover up the secretion proteins (cf.III.2.f).9 constituents of carbohydrates could be identified in uterine fluid. There was no evidence for freemonohexoses, particularly free glucose. Theoligomere carbohydrates were free or bound to proteins (cf.III.3.). We were able to separate Glycoprotein I, Glycoprotein II, Albumin + Uteroglobin with Sephadex G 150 and G 75 SF (cf.III.4).21 freeamino acids were found in uterine and blastocoelic fluid by means of thin layer chromatography. The concentrations of amino acids in uterine fluid were comparable to those of serum. The dry substance of uterine fluid contains more glycine, alanine, glutamic acid and aspartic acid than that of serum (cf.III.5).The possible role of amino acids in thenutrition of the blastocyst and the possible influence of uterine specific proteins and glycoproteins onnutrition and morphogenesis of the rabbit embryo were discussed.