Direct evidence that the brain reward system is involved in the control of scratching behaviors induced by acute and chronic itch

In the present study, we demonstrated that there is a direct relationship between scratching behaviors induced by itch and functional changes in brain reward system. Using conditional place preference test, rewarding effect was clearly evoked under both acute chronic stimuli. The induction of ΔFosB, member Fos family transcription factors, observed dopamine transporter (DAT)-positive neurons ventral tegmental area (VTA) mice suffering from sensation. Based on cellular analysis scratching-activated neurons, these highly expressed tyrosine hydroxylase (TH) DAT genes VTA. Furthermore, an vivo microdialysis levels extracellular nucleus accumbens (NAcc) were significantly increased transient behaviors. To specifically suppress mesolimbic dopaminergic pathway using pharmacogenetics, used TH-cre/hM4Di mice. Pharmacogenetic suppression decreased Under condition with restricted Elizabethan collar, ΔFosB found mostly corticotropin-releasing hormone (CRH)-containing hypothalamic paraventricular (PVN). These findings suggest repetitive abnormal stimuli may activate along pleasant emotions, while restriction such initially induce activation PVN-CRH associated stress.