Lesions to ascending noradrenergic and serotonergic pathways modify antinociception produced by intracerebroventricular administration of morphine.

TL;DR: Local peripheral ipsilateral, but not contralateral, pre-treatment with fluoxetine increased in a dose-dependent fashion 0.3-3 nmol/paw and prevented nociception induced by formalin, which produced a typical pattern of flinching and licking/lifting behaviors.

TL;DR: Results suggest a significant role of serotonin up-regulation in the spinal cord during chronic pain and the development of morphine tolerance in arthritic rats.

TL;DR: In this article, the effect of serotonin inhibition by the 5-HT3 receptor antagonist, ondansetron (OND), as well as serotonin deprivation via its synthesis inhibitor para-chlorophenylalanine, on mouse OIH was investigated, with particular focus on astrocyte activation.

TL;DR: Results support the involvement of GABAA receptors in modulating the action of opioids on the noradrenergic system in the cerebral cortex of the rat.

TL;DR: Evidence is presented that the intrinsic neural network that monitors and modulates the activity of pain‐transmitting neurons is mediated in part by endogenous opiatelike compounds (endorphins).

TL;DR: The intent of this review is to examine and synthesize the extensive progress that has been made in the last few years describing the anatomical, physiological and neurohumoral substrates of neural systems which modulate pain perception.

TL;DR: Opiate receptor distribution, determined by the autoradiographic localization of stereospecific [3H]diprenorphine binding sites, was examined in the telencephalon and the significance of these findings is discussed in terms of the biochemical and physiological actions of opiates.