Glycosylation is the enzymatic addition of oligosaccharides (also known as glycans) to proteins and lipids. Moreover, altered glycosylation is present in many pathophysiological conditions such as cancer, inflammation, autoimmune and aging .There were found significant changes in N-glycan´s composition in the sera of type 2 diebetes mellitus patients compared to healthy controls . Glycomic studies on rat serum have revealed that variations in the N-glycans of glycoproteins correlated with disease progression, which is consistent with the findings in human serum . The main goal of our study was to describe the N-glycans glycoprofiles of different rats strains and to evaluate their differences according to their structural type.
The 15 weeks old male Wistar (W) and hereditary hypertriglyceridemic rats (hHTG) fed 5 weeks standard diet (SD) were used. The analysis of serum N-glycoprofile was done by mass spectrometry analytics on MALDI TOF/TOF instrumentation. Blood serum samples were treated according to standard protein reduction and alkylation protocols . To release the N-glycans, serum was incubated with 1 U of PNGase F at 37°C overnight. Isolation of N-glycans was performed by PGC SPE . To increase the signal intensities and stabilize the sialic acid, N-glycans were subjected to permethylation . Analyzed data were processed by FlexAnalysis (Bruker Daltonics) and GlycoWork Bench  software. Obtained MS and representative MS/MS spectra of free and permethylated N-glycans were compared and evaluated with special focus on N-glycan type.
The cluster of 22N-glycans was appointed and sorted with special impact on their structural type. The changes in relative intensities of N-glycans were not significant, however, there were observed some trends in its remodelation within different rats strains. In W group there was detected higher percentage of high-manose N-glycan type. In hHTG group was higher portion of complex-bi-antennary and complex-bi-antennary N-glycans with fucose.
Up to this date, little is known regarding the changes in N-glycans during metabolic disturbances in rodents, but observed similarities between the glycomic profile of rat and human sera provided important selection criteria for choosing an appropriate animal model for pathological and/or further pharmacological studies . Our data have designated the fundamental basis for further research of glycosylation changes within animal models of civilization diseases.