The analgesic effects of intrathecally pumped saline and artificial cerebrospinal fluid in a rat model of neuropathic pain.

Objective. This experiment was performed to test the hypothesis that intrathecally pumped saline, but not artificial cerebrospinal fluid (CSF), would be analgesic in a rat model of neuropathic pain. Materials and Methods. Surgery for the chronic constriction injury (CCI) model of neuropathic pain and intrathecal catheter placement were performed on the rats, baseline pain testing and pump implantation were performed 7 days later, and pain tests were repeated on days 1, 4, 7, and 14 after pump implantation. Results. Intrathecally pumped saline and artificial CSF were analgesic for cold allodynia (p < 0.05), and intrathecally pumped saline but not CSF for heat nociception in the affected paw (p < 0.005) compared to rats with unattached subcutaneous pumps. No analgesia was observed on tests of spontaneous pain or pressure hyperalgesia (p > 0.1). Conclusions. Intrathecally pumped saline and artificial CSF have analgesic effects on some neuropathic and normal, nociceptive pain signs in CCI rats.