A Mechanistic Evaluation of the Interactions Between Thermoceptive and Pruriceptive Sensory Processing

Aalborg University59 enrolled

Overview

The purpose of this human experimental study is to evaluate the pattern of itch intensity over time in response to strong, short-term heat stimulation in two different models of histamine and cowhage-induced itch. Moreover, the purpose is to evaluate the effect of mild pre-heating of the skin in human experimental models of histamine, cowhage and serotonin. Finally, we want to investigate the effect of short-term intense heat stimulation on previously anesthetized skin.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Enrollment

Conditions

Itch Thermal Stimulation Histamine Cowhage Serotonine

LidocaineDRUG

Lidocaine intradermal injection

HistamineOTHER

Skin Prick Test with Histamine

CowhageOTHER

Manually skin insertion of cowhage spicules

Heat stimulationOTHER

Short heat stimulation

Pre-heatingOTHER

Mild skin pre-heating

SerotoninOTHER

Serotonin electrophoresis

Eligibility

Sex: ALLMin age: 18 YearsMax age: 60 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Healthy men and women * Age 18-60 years * Able to speak and understand English Exclusion Criteria: * Suffering from chronic disease * Pregnancy or lactation * Prior experience of adverse effects from anaesthetic, specifically Lidocaine * Drug addiction defined as the use of cannabis, opioids or other drugs - 5 - * Previous neurologic, musculoskeletal or mental illnesses * Lack of ability to cooperate * Current use of medications that may affect the trial * Active skin diseases * Active participation in other experiments currently ongoing or within the last 14 days * Tattoos on volar forearms that will interfere with local skin measurements

Outcomes

Primary Outcomes

eVAS Itch

Electronic Visual Analog Scale for itch sensation. 0-100 scale, it measures the self-estimated itch the subject experience on a scale where 0 correspond to "No itch" and 100 "Worst itch imaginable".

Time frame: 10 minutes

Skin temperature

Infrared skin thermometer

Time frame: 5 seconds

eVAS Pain

Electronic Visual Analog Scale for pain sensation. 0-100 scale, it measures the self-estimated pain the subject experience on a scale where 0 correspond to "No pain" and 100 "Worst pain imaginable".