Pentoxifylline modifies central and peripheral vagal mechanism in acute and chronic pain models.

The inflammatory process gives the way to hyperalgesia that is documented by the animal experimental studies. Pentoxifylline (PTX) has strong antyinflamatory effects, decreases TNF-alpha and other proinflammatory cytokines production. Therefore, the aim of present investigation was to evaluate the effectiveness of PTX in nociception processes, especially in aspects of vagal activity, in experimental pain models: visceral pain (VP), neuropathy (CCI) and neurogenic inflammation (NI). In VP and CCI models we observed significant increase in the pain threshold after blocking proinflammatory cytokines whereas in NI there was no such effect. In our studies we also observed the increase of vagal afferents activity in VP and CCI, on the contrary to NI model. In summary, our study demonstrates that preemptive inhibition of proinflammatory cytokine synthesis by treatment with PTX is useful in antagonizing hyperalgesia in inflammatory pain. Pentoxifylline reduces central and peripheral sensitization processes depend on the vagal component in both acute and chronic pain models but in a different manner and mechanisms. Our results establish the participation of inflammatory and vagal component in nociception. The modulation of the vagal system offers the new possibilities of the pain treatment in patients resistant to the classical analgesic therapy.