Neurogenic Amplification of Pancreatitis Pain

Many patients with pancreatitis or pancreatic cancer complain of abdominal pain that is resistant even to morphine. Our previous studies have determined that pain in patients with cancer involving the pelvic visceral organs is relieved by a neurosurgical lesion limited to the midline of the dorsal column of the spinal cord. We determined that sensory input from the pancreas is primarily transmitted to higher brain sensory processing centers as a midline component of the postsynaptic dorsal column pathway using anatomical, electrophysiological and behavioral methods. In our laboratory recently we have developed a model of persistent visceral pain in Lewis inbred rats that resembles human pancreatitis in blood values and histology. The purpose of the proposed project is to study the neuronal pathway by which pain signals from the pancreas reach higher brain centers and how sensitization of this pathway can lead to persistent pain states. A multidisciplinary approach is used including behavioral, electrophysiological, and functional magnetic resonance imaging (fMRI) methods. The following hypothesis and specific aims were devised to improve our understanding of chronic visceral pain processing toward the long term goal of improved therapy: HYPOTHESIS: Nociceptive information arising from the inflamed pancreas is relayed in the spinal cord, transmitted through medially ascending pathways to higher centers, and produces central sensitization in medially located brain structures. Specific Aim 1 is to determine the nociceptive pathways activated in persistent pancreatitis. Specific Aim 2 is to reduce activation in the visceral nociceptive pathways maintaining central sensitization in a persistent pancreatitis model in Lewis inbred rats. The long-term outcome expected is that information about the visceral nociceptive pathway will contribute to future identification of therapeutic targets for these devastatingly painful conditions involving the pancreas.