Glycosphingolipid composition of rat placenta: changes associated with stage of pregnancy

Abstract

The composition of glycolipids and their changes in the placenta were investigated in the normal pregnant rat. Total lipid fractions extracted from the placenta between days 12 and 20 of pregnancy (day 0 = oestrus) were subjected to glycolipid analysis using DEAE-Sephadex chromatography, silica-gel HPLC, silica-gel TLC, TLC/immunostaining, matrix-assisted secondary-ion mass spectrometry in the negative-ion mode and 1H NMR. Glycolipids identified in the rat placenta were: gangliosides GM3 (NeuAcLacCer and NeuGcLacCer) and GD3 (NeuAcNeuAcLacCer, NeuAcNeuGcLacCer and NeuGcNeuAcLacCer), and neutral glycolipids ceramide monosaccharide (CMH) (GlcCer), ceramide disaccharide (CDH) (LacCer), ceramide trisaccharide (CTH) (Gb3Cer) and ceramide tetrasaccharide (CQH) (Gb4Cer). The content of neutral glycolipids was higher than that of gangliosides throughout pregnancy. Of the neutral glycolipids, CMH and CTH predominated and the level of CDH was low at mid-pregnancy. During late pregnancy, CMH and CTH decreased and CDH increased markedly. CQH remained at a low level throughout pregnancy. Of the gangliosides, GM3 was predominant on days 12-16 and then decreased, whereas GD3, which was low on day 12, increased slightly on day 16 and maintained the same level thereafter. Immunohistochemical studies indicated that these changes in the expression of major gangliosides from GM3 to GD3 occurred in labyrinthine trophoblasts. Thus expression of these glycolipids appears to change markedly during pregnancy.

An Interspecies Comparison of Placental Gangliosides.

“…2B and 2C). GD3 from the rat placental extract, contained the NeuAc-NeuAc-, NeuAc-NeuGc-and NeuGc-NeuAc-sugar sequences [10]. The lower band of GD3 was not stained by the MECTOLONE-015 and R24 antibodies, suggesting this band was GD3 (NeuGc-NeuAc-).…”

“…togens [5][6][7][8] and expression of plasma membrane proteins [9] and gangliosides [10]. We reported that the major gangliosides present in the rat placenta were GM3 and GD3 [10]: GM3 predominated during mid-pregnancy and its levels declined during late pregnancy, whereas the converse was observed for GD3.…”

“…The production and characterization of these monoclonal antibodies have been described previously [13][14][15][16][17] and the culture supernatant of each hybridoma was used as an antibody source. A mouse monoclonal antibody, MECTOLONE-015, which is reactive with GD3 (NeuAc-NeuAc-) and moderately cross-reactive with GM3 (NeuAc), was a gift from Mect Co. (Tokyo, Japan) [10]. A mouse monoclonal antibody, R24, which was produced by immunization against SK-MEL-28 melanoma cells and is reactive with GD3 (NeuAc-NeuAc-and NeuAc-NeuGc-) gangliosides [18][19][20], was purchased from Signet Laboratories Inc. (Dedham, MA, U.S.A.).…”

“…We reported that the major gangliosides present in the rat placenta were GM3 and GD3 [10]: GM3 predominated during mid-pregnancy and its levels declined during late pregnancy, whereas the converse was observed for GD3. Thus, the ganglioside composition changed markedly according to the stage of pregnancy.…”

“…Therefore, conserved placental ganglioside expression implys a specific biological role of gangliosides in the placenta for expression of pregnancy stage-specific functions. The objective of the present study was to determine the major ganglioside components of the placentas of the sea lion, porpoise, cow and horse and compare them with those of the rat and human [10][11][12].…”