Fig. 5

Exposing sensory neuronal cultures to PGE₂ or to the EP4 receptor agonist L902688 for 5 days desensitizes the agonist-induced increase in PKA activity. a Each column represents the mean ± SEM of the treatment-stimulated PKA activity normalized to total PKA activity from cultures grown in the absence of added NGF and treated with vehicle or PGE₂ (1 μM) for 5 days as indicated. Cultures were washed and then re-exposed for 10 min to vehicle (open columns), 1 μM PGE₂ (closed columns) or 10 μM PGE₂ (hatched column). b Each column represents mean ± SEM of total specific activity of PKA after exposure to 10 μM cAMP from cultures treated with vehicle or PGE₂ (1 μM) for 5 days as indicated. Cultures were washed then re-exposed for 10 min to vehicle (open columns) or 1 μM PGE₂ (closed columns). c Each column represents the mean ± SEM of the treatment-stimulated PKA activity normalized to total PKA activity from cultures treated with vehicle, 300 nM L902688, or PGE₂ (1 μM) for 5 days as indicated. Cultures were washed and then re-exposed for 10 min to vehicle (open columns) or 300 nM L902688 (closed columns). An asterisk indicates a statistically significant difference from vehicle using one-way ANOVA followed by Bonferroni’s post hoc test