INTRODUCTION: Opioid @entity1337 can be explored with quantitative sensory testing, but most investigations have used models of @entity158 , and such brief stimuli may be limited in the ability to faithfully simulate natural and clinical @entity158 experiences. Therefore, identification of appropriate experimental @entity158 models is critical for our understanding of opioid effects with the potential to improve treatment. OBJECTIVES: The aim was to explore and compare @entity158 models to @entity1286 @entity1337 in healthy volunteers. METHODS: The study was a double-blind, randomized, two-way crossover study. Thirty-nine healthy @entity1 were included and received @entity1286 30 mg (2 mg/mL) as oral solution or placebo. To cover both tonic and phasic stimulations, a comprehensive multi-modal, multi-tissue @entity158 -testing program was performed. RESULTS: Tonic experimental @entity158 models were sensitive to @entity1286 @entity1337 compared to placebo: muscle pressure (F=4.87, P=0.03), bone pressure (F=3.98, P=0.05), rectal pressure (F=4.25, P=0.04), and the cold pressor test (F=25.3, P<0.001). Compared to placebo, @entity1286 increased tolerance to muscle stimulation by 14.07%; bone stimulation by 9.72%; rectal mechanical stimulation by 20.40%, and @entity158 reported during the cold pressor test by 9.14%. In contrast, the more phasic experimental @entity158 models were not sensitive to @entity1286 @entity1337 : skin heat, rectal electrical stimulation, or rectal heat stimulation (all P>0.05). CONCLUSION: @entity158 models with deep tonic stimulation including @entity7183 activation and and/or @entity158 modulation were more sensitive to @entity1286 @entity1337 . To avoid false negative results in future studies, we recommend inclusion of reproducible @entity158 models in deep tissues, mimicking clinical @entity158 to a higher degree.

Sensitivity of quantitative sensory models to XXXX @entity1337 in @entity1 .

@entity1 :: ('9606', 'Species') :: ['participants'] @entity1337 :: ('MESH:D000699', 'Disease') :: ['analgesia'] @entity7183 :: ('10185', 'Species') :: ['C fiber'] @entity1286 :: ('MESH:D009020', 'Chemical') :: ['morphine'] @entity158 :: ('MESH:D010146', 'Disease') :: ['Pain', 'phasic pain', 'tonic pain', 'pain', 'reduced pain', 'various pain', 'painful', 'endogenous pain']
@entity1286 :: (MESH:D009020,Chemical) :: ['morphine']
