Intrathecal injection of cell-permeable analogs of cyclic 3′, 5′-guanosine monophosphate produces hyperalgesia in mice

Several recent studies suggest that spinal cord levels of cyclic 3',5'-guanosine monophosphate (cGMP) may participate in the development of hyperalgesia. The purpose of this study was to directly evaluate whether cell permeable analogues of cGMP evoke a thermal hyperalgesia (using a hot-plate assay) when administered intrathecally in mice. Our results indicate that two cell permeable forms of cGMP evoke a dose dependent hyperalgesia when administered intrathecally in mice. Additionally, this hyperalgesia was selective since neither non-cell permeant cGMP nor guanosine had any effect on the latency of paw withdrawal when compared to the vehicle injected controls. These data indicate that cGMP is involved in the facilitation of thermal hyperalgesia at the level of the spinal cord.