The Interplay between Cyclic AMP, MAPK, and NF-κB Pathways in Response to Proinflammatory Signals in Microglia

Figure 6

Antagonism of PDE4, PKA, MEK, and NF-κB reduces cyclic AMP-dependent PDE activity in TNF-α stimulated microglia. In TNF-α stimulated microglia, the effect of antagonism of PKA, MEK, and NF-κB on pde4b2 expression was measured using Q-PCR (a). At 3 h after exposure to TNF-α, pde4b2 mRNA expression increased 2.5–3.0-fold in microglia compared to untreated controls, similar to that previously reported [21]. The addition of m-PKI or JSH-23, but not PD98059, showed a trend for a reduction in pde4b2 expression, though it was not statistically significant at this time point. Next, the effect of inhibiting PDE4, PKA, MEK, and NF-κB on cyclic AMP-dependent PDE activity in microglia at 3 h after TNF-α challenge was investigated (b). Compared to TNF-α only stimulated controls (gray bar), the addition of Rolipram (red bar), m-PKI (blue bar), PD98059 (yellow bar), or JSH-23 (green bar) all significantly reduced cyclic AMP-dependent PDE activity by at least 50%. The results shown are obtained from three independent culture plate replicates for each treatment condition. Errors are given as SEMs. Statistical significance versus TNF-α stimulated cells is given at .

(a)

(b)