Glial activation and segmental upregulation of interleukin-1β (IL-1β) in the rat spinal cord after surgical incision

The present study investigated the expression patterns of glial cells and interleukin-1 beta (IL-1 beta) in the rat spinal cord after a surgical incision, which is closely related with clinical postoperative pain. Microglia and astrocytes became activated in the spinal cord following incision. Real-time polymerase chain reaction (PCR) and immunohistochemisty showed that IL-1 beta mRNA and protein level in the spinal cord was transiently upregulated after surgical incision. The increased IL-1 beta-immunoreactivity (IR) was mainly localized in neurons but not the activated microglia or astrocytes. Although obvious increase in IL-1 beta-IR could be observed in the lumbar segments of the spinal cord ipsilateral to a hind paw incision, significant upregulation of IL-1 beta was not detected in the lumbar segments following thoracic incision. The present study indicated that surgical incision could induce glial activation and segmental upregulation of IL-1 beta in the spinal cord. The activated glial cells and upregulated IL-1 beta, in turn, may be involved in the incision-induced pain hypersensitivity.