Diazepam and rolipram differentially inhibit cyclic AMP-specific phosphodiesterases PDE4A1 and PDE4B3 in the mouse

Cyclic AMP is hydrolyzed by members of at least eight classes of cyclic nuc leotide phosphodiesterases (PDEs). Although it has been reported that cycli c AMP PDE activity in mammalian tissues can be inhibited by benzodiazepines , it has not been conclusively demonstrated that members of the class of cy clic AMP-specific, rolipram-inhibitable PDEs (PDE4s) are targets for these drugs. Moreover, no PDE4s expressed in mice have been characterized. To add ress these issues, we isolated two cDNAs representing homologues of PDE4A1 and PDE4B3 from a mouse brain library. After transient transfection in huma n embryonic kidney (HEK) 293 cells, the mouse PDEs hydrolyzed cyclic AMP wi th a low K-m and were inhibited by rolipram: both are properties typical of other mammalian PDE4 enzymes. In addition. we found that diazepam inhibite d cyclic AMP hydrolysis by the mouse PDE4 subtypes. Interestingly, PDE4B wa s significantly more sensitive to inhibition by both rolipram and diazepam than the PDE4A subtype. This is the first demonstration that recombinantly expressed PDE4s are inhibited by diazepam, and should facilitate future stu dies with mouse models of depression and anxiety. (C) 2001 Elsevier Science B.V. All rights reserved.