Signal changes in the spinal cord of the rat after injection of formalin into the hindpaw: Characterization using functional magnetic resonance imaging

Róbert Pórszász, Nicolau Beckmann, Konrad Bruttel, Laszlo Urban, Markus Rudin

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Changes in metabolism and local circulation occur in the spinal cord during peripheral noxious stimulation. Evidence is presented that this stimulation also causes signal intensity alterations in functional magnetic resonance images of the spinal cord during formalin-induced pain. These results indicate the potential of functional magnetic resonance imaging in assessing noninvasively the extent and intensity of spinal cord excitation in this well characterized pain model. Therefore, the aim of this study was to establish functional magnetic resonance imaging as a noninvasive method to characterize temporal changes in the spinal cord after a single injection of 50 μl of formalin subcutaneously into the hindpaw of the anesthetized rat. This challenge produced a biphasic licking activity in the freely moving conscious animal. Images of the spinal cord were acquired within 2 min, enabling monitoring of the site and the temporal evolution of the signal changes during the development of formalin-induced hyperalgesia without the need of any surgical procedure. The time course of changes in the spinal curd functional image in the isoflurane-anesthetized animal was similar to that obtained from behavioral experiments. Also, comparable physiological data, control experiments, and the inhibition of a response through application of the local anesthetic agent lidocaine indicate that the signal changes observed after formalin injection were specifically related to excitability changes in the relevant segments of the lumbar spinal cord. This approach could be useful to characterize different models of pain and hyperalgesia and, more importantly, to evaluate effects of analgesic drugs.

Original languageEnglish
Pages (from-to)5034-5039
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume94
Issue number10
DOIs
Publication statusPublished - May 13 1997

ASJC Scopus subject areas

  • General

Fingerprint Dive into the research topics of 'Signal changes in the spinal cord of the rat after injection of formalin into the hindpaw: Characterization using functional magnetic resonance imaging'. Together they form a unique fingerprint.

  • Cite this