Previous PET and fMRI brain imaging studies targeting neural networks processing itch sensation have used histamine as the sole itch inducer. In contrast with histamine, cowhage-induced itch is mediated via proteinase activated receptors PAR2 and is transmitted through a separate spinothalamic pathway, therefore imaging the brain activation evoked by cowhage could provide further insight into c...

PURPOSE The purpose of the study was to examine the symptom of itch and its relationship with chronic venous disease, pain, and quality of life. DESIGN The study used an exploratory, cross-sectional design. METHODS One hundred and sixty-one participants completed demographic, health, substance abuse, itch, and pain questionnaires and the SF-12v2 Health Survey to measure health related quali...

When a newly developed experimental method to vibrate vellus hairs on human skin was applied to the face and arm in healthy subjects, intense itch was reproducibly induced on the face, but not on the arm, without any flare reactions. In contrast to histamine-induced itch, mechanically evoked itch was not characterized as burning or stinging by any subjects, and was resistant to histamine H1-rec...

The association between itch and suicidal ideation has not been explored previously in the general population. The aim of the present study is to analyse the association between itch and suicidal ideation in adolescents, and to compare the findings with an expected association between pain and suicidal ideation in the same sample. A total of 4,744 adolescents were invited to join the questionna...

This Review highlights selected frontiers in pruritus research and focuses on recently attained insights into the neurophysiological, neuroimmunological, and neuroendocrine mechanisms underlying skin-derived itch (pruritogenic pruritus), which may affect future antipruritic strategies. Special attention is paid to newly identified itch-specific neuronal pathways in the spinothalamic tract that ...

Itch is the major symptom of many allergic or inflammatory skin diseases, yet it is still difficult to measure objectively. This article shows and updates the development and approaches of central nervous system investigation of itch.Human neuroimaging studies on the physiology and pathophysiology of itch sensation have been hampered by the lack of a reproducible "on-off" stimulus. Short-term a...

Increasing evidence suggests that Toll-like receptor 4 (TLR4) contributes importantly to spinal cord glial activation and chronic pain sensitization; however, its unique role in acute and chronic itch is unclear. In this study, we investigated the involvement of TLR4 in acute and chronic itch models in male mice using both transgenic and pharmacological approaches. Tlr4 mice exhibited normal ac...

Chronic itch, or pruritus, is associated with a wide range of skin abnormalities. The mechanisms responsible for chronic itch induction and persistence remain unclear. We developed a mouse model in which a constitutively active form of the serine/threonine kinase BRAF was expressed in neurons gated by the sodium channel Nav1.8 (BRAF(Nav1.8) mice). We found that constitutive BRAF pathway activat...

The neurophysiology of itch, the dominant symptom of skin disease, has previously received scant attention. Recent advances in the neurophysiology and molecular basis of itch include the use of microneurography to demonstrate the existence of a subset of itch-dedicated afferent C neurons distinct from neurons which transmit pain; use of functional positron emission tomography (PET) and magnetic...

How neuropeptides in the primate spinal cord regulate itch and pain is largely unknown. Here we elucidate the sensory functions of spinal opioid-related peptides and gastrin-releasing peptide (GRP) in awake, behaving monkeys. Following intrathecal administration, β-endorphin (10-100 nmol) and GRP (1-10 nmol) dose-dependently elicit the same degree of robust itch scratching, which can be inhibit...