The Role of the Endocannabinoids During the Analgesia Caused by Hypnosis and Meditation

Introduction: Many interventions such as hypnosis, mindfulness meditation, conditioned pain modulation and placebos have been shown to effectively reduce pain both in the laboratory and in clinical settings. However, little is known about their neurophysiological mechanisms of action. Analgesia induced by these techniques is thought to be based on opioidergic and non-opioidergic mechanisms (potentially endocannabinoid mechanisms). Objective: Our main objective is to evaluate the effect of hypnosis, meditation, conditioned pain modulation and placebo on blood concentrations of endocannabinoids (anandamide, 2-arachidonylglycerol, N-palmitoyl-ethanolamine, N-oleoylethanolamide), endogenous opioids (β-endorphins, met / leu-enkephalins, and dynorphins) and norepinephrine in healthy adults. Methods: This study is based on a single-group pre-experimental research design in which two experimental sessions including hypnosis or meditation, conditioned pain modulation and placebo interventions will be completed by all participants. In order to have a better description of the sociodemographic and clinical characteristics of the sample, information will be collected by questionnaires or tests filled by participants at baseline, including: age, sex, language, culture, religion, salary, menstrual cycle of women, medication (if any), mood, anxiety, pain catastrophizing, mindfulness, hypnotic susceptibility, and DNA information. Outcome measures will be collected before, during and after each intervention. The primary outcome is plasma concentrations of endocannabinoids. Secondary measurements include plasma concentrations of endogenous opioids and norepinephrine; change in pain intensity during the thermal noxious stimuli; and autonomic nervous system variability (as measured by heart rate variability). Anticipated results: The investigators expect a positive relationship between the change in pain intensity (analgesia) induced by the interventions (hypnosis, meditation, conditioned pain modulation, and placebo) and the change (increase) in plasma concentrations of endocannabinoids, opioids, and norepinephrine in healthy adults. It is also believed that the interventions will influence heart rate variability. Moreover, it is expected that there will be a relationship between the efficiency of the analgesic intervention and some gene polymorphisms associated to pain modulation and endocannabinoids, opioids or norepinephrine in healthy individuals.