Objectives: The objective of this article is to try to bring a discussion in light of the serotoninergic pathways and their effects on the pain modulatory circuits in order to understand the action of drugs that help in the treatment of the various pain syndromes.

Discussion: It is well established that monoamines have complex modulatory functions in pain signaling. Topdown processing pathways arise in the structures of the midbrain and brainstem and exert a powerful inhibitory or excitatory control over the neuronal responses of the dorsal horn; predominantly through the actions of neurotransmitters, of which serotonin [5-HydroxyTryptamine (5-HT)] stands out, which in turn acts on specific receptor subtypes. The peripheral pro-nociceptive role of 5-HT is well defined to date; in contrast, its action at the level of the spinal cord and supraspinal structures seems highly variable and remains a question under discussion.

Conclusion: In the presence of 5-HT 1, 5-HT 2, 5-HT 3 and 5-HT 7 receptors in different amounts and at different levels, pain inhibition has been reported for most of these studies. However, some studies mention the involvement of these receptors in hyperalgesia, or even the maintenance of the pain stimulus.