Efeito do tratamento com glucosamina no teste de tolerância à glicose e na expressão proteica de O-glicosilação e OGT no tecido tímico de ratos

Abstract

The thymus is an important organ for T cell production, and activation of these cells requires metabolic changes, including increased aerobic glycolysis and flux in the pentose phosphate pathway. These metabolic processes result in the production of substrates for the synthesis of N-acetyl-glucosamine uridine diphosphate, which leads to increased levels of O-GlcNAc, a post-translational modification of proteins associated with nutritional regulation. The addition and removal of N-acetyl-glucosamine is catalyzed by two enzymes, O-GlcNAc transferesa (OGT) and O-GlcNAcase (OGA), respectively. OGT is also involved in activating the T cell receptor signaling pathway. However, little is known about the role of this process in the thymus. The aim of this study was to evaluate the protein expression of O-GlcNAc and OGT in the thymus of animals treated with glucosamine, in addition to investigating the involvement of glucose in this process using the oral glucose tolerance test (OGTT). The animals in group A were treated with saline and those in group B with glucosamine (dose 300mg/kg), for 21 days and, on the last day, OGTwas performed after a 6-hour fast. The thymus was collected at the end of the treatment for Western Blot analysis. Analysis of the results revealed that glucosamine treatment stimulated OGT expression and increased O- glycosylation in the thymus. Regarding glycemic levels, the group treated with glucosamine showed a glycemic peak at 30 minutes of OGTT, but did not show significant changes at 60 and 120 minutes. It is concluded that glucosamine stimulates OGT expression, resulting in increased O-glycosylation in the thymus. Although glucosamine treatment did not significantly affect glycemic levels, the results suggest that the overall increase in O-GlcNAc is directly related to glucosamine availability.