ROLE OF TNF-ALPHA BUT NOT NGF IN MURINE HYPERALGESIA INDUCED BY PARASITIC INFECTION

Using adult mice infected with the trematode Schistosoma mansoni, we o bserved that this infection induces both thermal hyperalgesia and an i ncrease in the levels of nerve growth factor in the paws. To explore t he mechanism involved in peripheral hypersensitivity during chronic in fection, mice were infected with 60 cercariae of S. mansoni and inject ed 17 weeks later with nerve growth factor, anti-nerve growth factor o r with other molecules known to be associated with hyperalgesic proces ses. The results of these studies showed that antibodies against tumor necrosis factor-alpha, but not against nerve growth factor, reduce th ermal sensitivity in schistosome infected mice, suggesting that this c ytokine but not NGF plays a crucial role in schistosome-induced therma l hyperalgesia. Treatments with anti-inflammatory drugs support this h ypothesis.