Brain nociceptive imaging in rats using 18f-fluorodeoxyglucose small-animal positron emission tomography

Y. Y.I. Shih, Y. C. Chiang, J. C. Chen, C. H. Huang, Y. Y. Chen, R. S. Liu, C. Chang*, F. S. Jaw

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Preclinical exploration of pain processing in the brain as well as evaluating pain-relief drugs in small animals embodies the potential biophysical effects in humans. However, it is difficult to measure nociception-related cerebral metabolic changes in vivo, especially in unanesthetized animals. The present study used 18F-fluorodeoxyglucose small-animal positron emission tomography to produce cerebral metabolic maps associated with formalin-induced nociception. Anesthesia was not applied during the uptake period so as to reduce possible confounding effects on pain processing in the brain. The formalin stimulation at the hind paw of rats resulted in significant metabolic increases in the bilateral cingulate cortex, motor cortex, primary somatosensory cortex, secondary somatosensory cortex, insular cortex, visual cortex, caudate putamen, hippocampus, periaqueductal gray, amygdala, thalamus, and hypothalamus. Among the measured areas, clear lateralization was only evident in the primary somatosensory cortex and hypothalamus. In addition, pretreatment with lidocaine (4 mg/kg, i.v.) and morphine (10 mg/kg, i.v.) significantly suppressed formalin-induced cerebral metabolic increases in these areas. The present protocol allowed identification of the brain areas involved in pain processing, and should be useful in further evaluations of the effects of new drugs and preclinical therapies for pain.

Original languageEnglish
Pages (from-to)1221-1226
Number of pages6
Issue number4
StatePublished - 9 Sep 2008


  • PET
  • lidocaine
  • morphine
  • pain
  • rat


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