Pain ThresholdEndorphinsbeta-EndorphinPainbeta-LipotropinAdrenocorticotropic HormoneMelanocyte-Stimulating HormonesPituitary Hormones, AnteriorPain MeasurementSensory ThresholdsPro-OpiomelanocortinPain PerceptionN-Terminal AcetyltransferasesTranscutaneous Electric Nerve StimulationNaloxonePituitary GlandPain ManagementEnkephalinsHyperalgesiaChronic PainThermosensingProtein PrecursorsPain, ReferredPain, PostoperativeAnalgesicsEar, ExternalDental Pulp TestAnalgesiaNociceptorsFibromyalgiaFacial PainRadioimmunoassayMunchausen Syndrome by ProxyLow Back PainHot TemperaturePressurePhysical StimulationNeck PainAcupuncture PointsAcupuncture AnalgesiaWristBack PainHypesthesiaMyofascial Pain SyndromesToothacheAnalgesics, OpioidSensationNociceptive PainNeuralgiaAbdominal PainAnalgesics, Non-NarcoticPain, IntractableDifferential ThresholdElectric Stimulation TherapyAuditory ThresholdPelvic PainAcupuncture TherapyHyperesthesiaElectroacupunctureSomatosensory DisordersElectric StimulationDouble-Blind MethodAcute PainIrritable Bowel SyndromeAnalysis of VarianceCold TemperatureRadial NerveMorphineTemporomandibular Joint Dysfunction SyndromeSkin TemperatureTime FactorsVibrationWhiplash InjuriesLidocaineMigraine DisordersAnesthetics, LocalChronic DiseaseCross-Over StudiesShoulder PainMusculoskeletal PainSkin Physiological PhenomenaEvoked Potentials, SomatosensoryPerceptionReproducibility of ResultsTouchQuestionnairesNAV1.7 Voltage-Gated Sodium ChannelSpinal CordPreanesthetic MedicationSkinNAV1.8 Voltage-Gated Sodium ChannelBehavior, AnimalInjections, SpinalSensation DisordersRats, Sprague-DawleyThoracic WallNAV1.9 Voltage-Gated Sodium ChannelPeriaqueductal GrayLasersAcetaminophen