FIGURE 5.

Effect of pretreatment with Morphine on metabolic changes in different brain areas of rats induced by formalin. Bars represent mean+S.E.M. ¹⁸F-FDG uptake normalised by the ¹⁸F-FDG uptake in the group that received intrathecal PBS. Pretreatment with intrathecal Morphine (10 µg/site) led to a reduction in the metabolic activity in some neuroanatomic regions, notably in the amygdala, striatum and accumebens. The definition of contra or ipsilateral was made in reference to the right paw where formalin or PBS was administered (N = 6 and N = 8, PBS and Morphine groups, respectivelly. ANOVAs with Fisher’s post hoc tests). WM: white matter, GM: gray matter, PAG: periaqueductal gray.