Dexamethasone effects on the expression and content of glycosylated components of mouse brain tissue

Abstract

Introduction. Glucocorticoids are actively used in the treatment of various diseases, however their long-term use leads to numerous negative side-effects, the molecular mechanisms of which remain poorly understood.Aim. Study of the short-term (1–10 days) effects of various doses of dexamethasone (Dex) (0,1–10 mg/kg) on the expression of the glucocorticoid receptor (GR, Nr3c1), core proteins of main proteoglycans and heparan sulfate metabolism-involved genes, as well as the content of carbohydrate macromolecules of glycosaminoglycans in the brain tissue of experimental animals.Materials and methods. In the study, C57Bl/6 mice were used. The expression of GR, proteoglycan core proteins and heparan sulfate metabolism-involved genes was determined by real-time polymerase chain reaction with reverse transcription. The content and localization of GR protein molecule were studied by Western blot and immunohistochemical analysis, and the glycosaminoglycan content was determined by dot-blot analysis and Alcian Blue staining.Results. It was shown that a single Dex administration leads to fast (1–3 days) short-term activation of GR expression (+1.5 times, p <0.05), proteoglycan’s genes (syndecan-3, Sdc3; perlecan, Hspg2; phosphacan, Ptprz1; neurocan, Ncan; +2–3-fold; p <0.05) and heparan sulfate-metabolism-involved genes (Ndst1, Glce, Hs2st1, Hs6st1, Sulf1 / 2; +1.5–2-fold; p <0.05) in the mouse brain, with a return to control values by 7–10 days after Dex administration. At the same time, the effect of Dex on carbohydrate macromolecules of glycosaminoglycans was more delayed and stable, increasing the content of low-sulfated glycosaminoglycans in the brain tissue in a dose-dependent manner starting from day 1 after Dex administration. Highly-sulfated glycosaminoglycans showed more delayed response to Dex administration, and an increase in their content was observed only at higher doses (2.5 and 10 mg/kg) and only on 7–10 days after its administration, apparently, mainly due to an increase in heparan sulfate content.Conclusion. In general, the effect of a single injection of Dex on the transcriptional activity of GR, proteoglycan core proteins and heparan sulfate metabolism-involved genes were short-termed, and the genes expression quickly returned to the normal levels. However, even a single use of Dex significantly increased the content of total as well as highly sulfated glycosaminoglycans in the mouse brain tissue, which can lead to the changes in the composition and structure of the brain tissue, as well as its functional characteristics.

Multiple Administration of Dexamethasone Possesses a Deferred Long-Term Effect to Glycosylated Components of Mouse Brain

“…Interestingly, a similar effect was observed upon incubation of DXM with organotypic culture of rat brain ex vivo and after multiple (1 week, daily) DXM administrations to Wistar rats, where DXM reduced the level of CS and HS molecules (2–2.5-fold) in both the cerebral cortex and hippocampus [ 26 ]. Multiple administration of 1 mg/kg DXM in the glioblastoma relapse experimental SCID mice model in vivo (3 cycles × 5 injections) also resulted in a decrease in CS content and HS in both normal and paratumorous brain tissues [ 31 , 32 ]. A decrease in the CS content was observed in the brains of Sprague–Dawley rats upon local implantation of DXM inside the silicone probes for prolonged control release at as early as 1 week of probe implantation [ 24 ].…”

“…It has been shown that Hs3St2 demonstrated increase on day 60, and Hs6St2 30 and 60 days after DXM administration. There are published data which show that a single administration of DXM can induce an increase in some HS biosynthetic enzymes (Ndst1, Glce, Hs2St1, Hs6St1, Sulf1, Sulf2), but this effect was short-term (3 days after DXM treatment injection) [ 31 ]. However, another study described that the transcriptional activity of HS biosynthetic systems was not affected by DXM administration in the normal brain tissue of SCID mice [ 32 ].…”

“…Chronic DXM administration at a dosage of 5 mg/kg for 7–28 days resulted in a 2-fold decrease in the level of GR content ( p < 0.01) in the mouse brain frontal cortex and hippocampus, and by 28 day, the content of GR was the lowest [ 30 ]. Chronic DXM exposure (5 μΜ for 3 days) significantly reduced the mRNA level of GR in the cultured Sprague–Dawley rat’s hippocampal neurons [ 31 ]. These data can indirectly support GR involvement in the transcriptional regulation of PG-metabolic genes.…”

The contribution of proteoglycans to heterogeneity and temozolomide resistance of glioblastoma cells

“…These data complement our previous results on the significant effects of TMZ on PG/GSG expression and composition in normal brain tissue in the animal models of GB relapse [47] . The TMZ-treated rat and mouse brain tissue was more susceptible to U87 GB cells, providing favorable conditions for the development of U87 xenografts in SCID mice [48] . Together, these results show that TMZ treatment affects PGs/GAGs in both GB cells and surrounding normal brain tissue and can take part in the mutual adaptation of the cancer cells with their microenvironment.…”