Peripheral participation of the phosphodiesterase 3 on formalin-evoked nociception.

The local peripheral (subcutaneous) injection of phosphodiesterase 3 inhibitor trequinsin dose-dependently enhanced formalin-evoked flinching during late second phase of this test. Treatment with the nitric oxide synthase inhibitor N-L-nitro-arginine methyl ester or guanylyl cyclase inhibitor 1-H-[1,2,4,]oxadiazolo[4,3-a]quinoxalin-1-one significantly reversed trequinsin-induced pronociceptive effect. Results suggest that the peripheral phosphodiesterase 3 may play an important physiologic role on inflammatory pain by controlling cyclic AMP levels and therefore the nociceptor threshold.