Figure 3.
Infusion of the Epac-specific agonist does not change PKA-dependent phosphorylation of GluR1 receptor subunits in the hippocampus. Phospho-GluR1 (pSer845) (A) and total GluR1 (B) levels in the hippocampus 15 or 45 min post-drug infusion (open and shaded bars, respectively). (A) pSer845 levels were significantly increased 15 min after unilateral infusion of Sp-cAMPS (4.5 μg) relative to the saline-treated side (*P = 0.04). Infusions of the Epac agonist or the combination of the agonist and PKI had no effect at either time point relative to their respective vehicle-treated hippocampi (8-pCPT-2′-O-Me-cAMP, 0.5 μg; PKI [4 μg] + 8-pCPT-2′-O-Me-cAMP [0.5 μg]). A strong trend (P = 0.06) toward an increase in pSer845 levels was observed for the Sp-cAMPS-infused hippocampi at 45 min. n = 5 for all treatment groups and time points. (B) Total GluR1 levels were unaffected by drug treatments at either time point. (C,D) Representative immunoblots of pSer845 (1:2000, Millipore), β-tubulin (1:20000, Sigma), and total GluR1 (1:2000, Millipore) levels 15 min (C) or 45 min (D) after infusion. All values were normalized to β-tubulin levels within individual samples to control for differences in total protein loaded, and then to mice that received mock injections (black bars in A and B, n = 4). Data are expressed as mean ± SEM.