The present study was designed to characterize the possible roles of spinally located cholera toxin (CTX)- and pertussis toxin (PTX)-sensitive G-proteins in pro-inflammatory cytokine induced pain behaviors. Intrathecal injection of tumor necrosis factor-alpha (TNF-alpha; 100 pg), interleukin-1beta (IL-1beta; 100 pg) and interferon-gamma (INF-gamma; 100 pg) showed pain behavior. Intrathecal pretreatment with CTX (0.05, 0.1 and 0.5 mg) attenuated pain behavior induced by TNF-alpha and INF-gamma administered intrathecally. But intrathecal pretreatment with CTX (0.05, 0.1 and 0.5 microg) did not attenuate pain behavior induced by IL-1beta. On the other hand, intrathecal pretreatment with PTX further increased the pain behavior induced by TNF-alpha and IL-1beta administered intrathecally, especially at the dose of 0.5 microg. But intrathecal pretreatment with PTX did not affect pain behavior induced by INF-gamma. Our results suggest that, at the spinal cord level, CTX- and PTX-sensitive G-proteins appear to play important roles in modulating pain behavior induced by pro-inflammatory cytokines administered spinally. Furthermore, TNF-alpha, IL-1beta and INF-gamma administered spinally appear to produce pain behavior by different mechanisms.
