Lipopolysaccharide administration in vivo induces differential expression of cAMP‐specific phosphodiesterase 4B mRNA splice variants in the mouse brain

Many inflammatory processes involve cAMP. Pharmacological manipulation of cAMP levels using specific phosphodiesterase (PDE) inhibitors provokes an antiinflammatory response. The aim of this study was to investigate changes in the pattern and levels of expression of mRNAs coding for the cAMP-specific PDE4 family and subfamilies in mouse brain during the immediate acute immune response provoked by an intraperitoneal injection of lipopolysaccharide (LPS). PDE4B, and furthermore the splice variants PDE4B2 and PDE4B3, were the only mRNAs that showed altered expression. Whereas PDE4B2 presented increased expression at both 3 and 8 hr postinjection, PDE4B3 mRNA showed decreased expression that reached a minimum 8 hr postinjection. PDE4B2 mRNA upregulation was observed mainly in endothelial and macrophage/neutrophil cell populations in the leptomeninges, and the downregulation of PDE4B3 was observed mainly in oligodendrocytes throughout the brain. Our results clearly illustrate the distinctive anatomical distribution and cellular localization of the PDE4Bs during neuroinflammation and emphasize the importance of PDE4B splice-variant-specific inhibitors as therapeutic tools.