Figure 8

Effect of δ-OR agonists, insulin, or PDGF on tyrosine phosphorylation of the insulin receptor or the PDGF receptor. C6-δ-OR cells were serum-starved overnight prior to exposure to DADEE (10 mM), DPDPE (10 mM), DSLET (10 mM), insulin (100 ng/ml), or PDGF (50 mg/ml) for 5 minutes. After agonist exposure, cell lysates were prepared and the IR or the PDGFR was immunoprecipitated as described in the methods section using the appropriate antibodies. Tyrosine phosphorylation of these receptors was determined by SDS PAGE, followed by immunoblotting of proteins onto nitrocellulose. Immunopositive bands correspond to the tyrosine-phosphorylated forms of the IR (open bars) or the PDGF (hatched bars). Phosphotyrosine bands were quantified using the MCID system. Phosphotyrosine band intensities are expressed graphically as: grain density × band area - [region of detection (ROD)] × pixel. Data points represent the mean ± SEM of three experiments. ^*p ≤ 0.05 compared to untreated samples as determined by ANOVA and the Tukey post-hoc test.