Figure 5: Adenosine A_2A receptors (A_2AR) modulate glucocorticoid response element (GRE) regulated luciferase expression in N1E115 cells and promote dexamethasone induced Glucocorticoid Receptor (GR) translocation to the nucleus.

(a) Dexamethasone induced an increase in luciferase activity (n = 8–17) (b) which is decreased upon A_2AR blockade by two antagonists, SCH 58261 (10–100 nM) and KW 6002 (50 nM) (n = 5–11) and (c) increased upon direct A_2AR activation with CGS 21680 (10–50 nM) (n = 3–9), as depicted in the upper schemes. Activation of A_2AR alone is sufficient to modulate endogenous GR transcriptional activity (d) A_2AR antagonist decreases luciferase activity (n = 6–14) while (e) A_2AR agonist increases it (n = 3–11). (f) A_2AR effects are prevented by the glucocorticoid receptor (GR) antagonist, RU 486 (100 nM, n = 5–10). Results are presented as mean ± SEM of n experiments. In (d–f) results were normalized to CTR, i.e., to the condition without dexamethasone, while in b) and c) results are normalized to DEX-induced activity. *P < 0.05 compared to control, ^ΦP < 0.05 compared with dexamethasone induced luciferase activity calculated using a one-way ANOVA followed by a Bonferroni post hoc test. (g) Left panel illustrates the gradual enrichment of GR in the nuclear fraction of neuronal cultures over time of exposure to dexamethasone (n = 2–4). This increase is completely prevented by blocking A_2AR with SCH 58261- 50 nM (in right panel). Results are presented as mean ± SEM of n experiments. *P < 0.05 compared to control, ^#P < 0.05 compared with dexamethasone calculated using two-way ANOVA followed by a Bonferroni post hoc. (h) Expression levels of GR and A_2AR in N1E115, compared to hippocampal (Hip) and cortical (Ctx) tissue.