Do nociceptive signals from the pancreas travel in the dorsal column?

A midline dorsal column lesion has been shown to be an effective surgical t reatment for the relief of pelvic visceral pain in patients. The aim of thi s study was to examine the effectiveness of a dorsal column lesion upon: (i ) increased electrophysiological responses of neurons in the ventral poster olateral thalamic nucleus in anesthetized rats evoked by the application of bradykinin to the surface of the pancreas, and (ii) pain-related behaviors observed after pancreatic infusion with bradykinin. In rats anesthetized w ith pentobarbital. recordings from individual thalamic neurons were made us ing tungsten electrodes. Brief application of bradykinin (10 mug/ml) to the surface of the pancreas resulted in an increased firing rate in approximat ely 20% of neurons recorded. A dorsal column lesion or intrathecal administ ration of morphine greatly reduced the excitatory effects of pancreatic bra dykinin application on thalamic neurons. In a separate group of rats, brady kinin was infused into the pancreas through a previously implanted catheter resulting in a decrease in exploratory behavior and an increase in other p ain-related behaviors, e.g. licking of the abdomen. A dorsal column lesion made prior (1 week) to the bradykinin infusion reduced the decrease in expl oratory behavior but did not return exploratory behavior to control levels. In conclusion, nociceptive information relayed to the thalamus about the p ancreas is transmitted from the spinal cord through the dorsal columns, pos sibly by the post-synaptic dorsal column pathway. However, the dorsal colum n pathway may not be the sole route for relaying information about noxious stimulation of the pancreas, particularly that impacting complex behavioral responses. (C) 2001 International Association for the Study of Pain. Publi shed by Elsevier Science B.V. All rights reserved.