Expression of O-linked N-acetylglucosamine in the Rat Brain during Pregnancy and Lactation
During pregnancy, adaptations occur in the maternal brain and body to ensure optimal nutrition for both the mother and fetus. Over nutrition in the mother can lead to gestational diabetes mellitus (GDM). GDM in mothers is a significant risk factor for development of cardiovascular disease and pre-eclampsia (Carr et al.,2011). The protein modification O-linked N-acetylglucosamine (O-GlcNAc) is derived from glucose through the hexosamine biosynthetic pathway (HBP) and has been shown to increase in hyperglycemic conditions and plays a role in the etiology of many diseases, including T2DM (Hart et al., 2011). Research on the changes of O-GlcNAcylation during pregnancy and lactation is scarce. My study aimed to determine any changes in O-GlcNAc expressing cells during the physiological conditions of pregnancy and lactation in the rat brain. I hypothesised that there would be an increased number of O-GlcNAc expressing cells during pregnancy due to higher blood glucose levels, which would normalise or decrease during lactation compared to non-pregnant rats. Female Sprague Dawley rats were divided into 3 groups (diestrus, 21 days pregnant and day 7 lactating), perfused with 4% paraformaldehyde, brains removed and coronally sliced for immunohistochemistry. Single-label chromogen staining for O-GlcNAc was carried out in the ventromedial hypothalamus (VMH), paraventricular nucleus (PVN), supraoptic nucleus (SON), periventricular nucleus (Pe) and the anteroventral periventricular nucleus (AVPV). Single-label immunofluorescence for O-GlcNAc was carried out in the arcuate nucleus (ARC). Sections were photographed and analysed using FIJI (Image J) to count the number of O-GlcNAc expressing cells in each area. There was no statistical difference between the number of O-GlcNAc expressing cells in pregnant and lactating rats compared with non-pregnant rats in the ARC, PVN, SON, VMH, Pe and AVPV. Double-label immunofluorescence for O-GlcNAc and DeltaFosB, a marker of chronic activation, was also carried out in the PVN. The average number of DeltaFosB expressing cells and O-GlcNAc expressing cells were counted, no difference was detected between the non-pregnant, pregnant and lactating groups. Furthermore, the percentage of DeltaFosB cells co-expressing O-GlcNAc and the percentage O-GlcNAc cells co-expressing DeltaFosB revealed no difference between the non-pregnant, pregnant and lactating groups. The results from our study suggests that in a normal rat pregnancy and subsequent lactation the expression of O-GlcNAc does not differ from non-pregnant expression.
Advisor: Augustine, Rachael
Degree Name: Bachelor of Biomedical Sciences with Honours
Degree Discipline: Physiology
Publisher: University of Otago
Keywords: O-GlcNAc; O-linked N-acetylglucosamine; Rat Brain; Pregnancy; Lactation
Research Type: Thesis