Injections, SpinalSpinal CordInjectionsHyperalgesiaAnesthesia, SpinalSpinal NervesAnalgesicsPainPain MeasurementSpinal Cord InjuriesMorphineRats, Sprague-DawleyNeuralgiaPain ThresholdAnalgesics, OpioidPosterior Horn CellsBupivacaineNeostigmineClonidineNociceptionAnesthetics, LocalSpinal Nerve RootsNociceptorsPeripheral Nerve InjuriesSubarachnoid SpaceAnalgesia, ObstetricalDose-Response Relationship, DrugAnesthesia, ObstetricalAnalgesiaInjections, IntravenousGanglia, SpinalDrug ToleranceCyclohexanecarboxylic AcidsInjections, IntramuscularBehavior, AnimalFentanylSciatic NeuropathyPhysical StimulationNaloxoneDisease Models, AnimalAnalgesics, Non-NarcoticInjections, SubcutaneousElectroacupunctureMeningeal NeoplasmsCesarean SectionSubstance PTime FactorsInjections, IntralesionalFormaldehydeSpinal Cord DiseasesInjections, Intra-ArticularReflexFreund's AdjuvantSciatic NerveNarcotic AntagonistsInfusion Pumps, ImplantableAdrenergic alpha-AgonistsAminesInjections, EpiduralInjections, IntraperitonealPeripheral Nervous System DiseasesMuscle Relaxants, CentralRats, WistarLigationInjections, IntraventricularSpinal CanalSpinal Cord NeoplasmsReceptors, N-Methyl-D-AspartateN-MethylaspartateCapsaicinSpinal DiseasesSpinal Cord CompressionDouble-Blind MethodSpinal NeoplasmsMice, Inbred C57BLMotor ActivityHot TemperatureInjections, IntradermalInfusions, SpinalSpinal StenosisSufentanilSpinal FusionMuscle SpasticityBaclofenInjections, Intra-ArterialPain, IntractableIntravitreal InjectionsLidocaineInjections, JetBlood PressureInjections, IntraocularSpinal Cord IschemiaSpinal InjuriesMuscular Atrophy, SpinalMeningesMicroinjectionsPruritusBlotting, WesternLumbosacral RegionMotor Neurons