A Brief Period of Moderate Noxious Stimulation Induces Hemorrhage and Impairs Locomotor Recovery after Spinal Cord Injury

Publication date: Available online 21 October 2019Source: Physiology & BehaviorAuthor(s): Misty M. Strain, Michelle A. Hook, Joshua D. Reynolds, Yung-Jen Huang, Melissa K. Henwood, James W. GrauABSTRACTSpinal cord injury (SCI) is often accompanied by additional tissue damage (polytrauma) that provides a source of pain input. Our studies suggest that this pain input may be detrimental to long-term recovery. In a rodent model, we have shown that engaging pain (nociceptive) fibers caudal to a lower thoracic contusion SCI impairs recovery of locomotor function and increases tissue loss (secondary injury) and hemorrhage at the site of injury. In these studies, nociceptive fibers were activated using intermittent electrical stimulation. The stimulation parameters were derived from earlier studies demonstrating that 6 min of noxious stimulation, at an intensity (1.5 mA) that engages unmyelinated C (pain) fibers, induces a form of maladaptive plasticity within the lumbosacral spinal cord. We hypothesized that both shorter bouts of nociceptive input and lower intensities of stimulation will decrease locomotor function and increase spinal cord hemorrhage when rats have a spinal cord contusion. To test this, the present study exposed rats to electrical stimulation 24 hours after a moderate lower thoracic contusion SCI. One group of rats received 1.5 mA stimulation for 0, 14.4, 72, or 180 seconds. Another group received six minutes of stimulation at 0, 0.17, 0.5, and 1.5 mA. Just 72 s of...
Source: Physiology and Behavior - Category: Physiology Source Type: research