Brain nociceptive imaging in rats using 18f-fluorodeoxyglucose small-animal positron emission tomography
Journal
Neuroscience
Journal Volume
155
Journal Issue
4
Pages
1221-1226
Date Issued
2008
Author(s)
Abstract
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 (18)F-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.
SDGs
Type
journal article