Endogenous Opioid and Cannabinoid Systems are Involved in NSAIDs-induced Antinociception in Brain Limbic Areas

Pain sensation is characterized as a complex experience, dependent on sensory processes but also
on the activation of emotional operations in limbic brain areas. A network analysis suggested that
there are broad-ranging, as well as specific changes with a focus on prefrontal regions, the anterior
insula, thalamus, anterior cingulate cortex, central amygdala, periaqueductal grey matter, and other
midbrain structures. This chapter provides an original account of behavioral aspects with important
ramifications for the study of brain mechanisms of analgesia by widely used non-steroidal antiinflammatory
drugs in rodent’s formalin test. It explains, in terms of specified somato-sensory
machinery and systems, mechanisms of antinociception by these non-opioid drugs in pain matrix key
structures of brain limbic areas, – the anterior cingulated cortex, agranular insular cortex, and central
amygdala, – with testing thermal and mechanical withdrawal reflexes in rats. In these experimental
paradigms, the chapter presents a study the roles of endogenous opioid and cannabinoid systems in
brain descending pain control mechanisms.