title: Thermal, mechanical and chemical peripheral sensation in amphibians: opioid and adrenergic effects.
abstract: The acetic acid test (AAT) is a quantifiable assay of the response to noxious chemical stimuli on the hindlimb of the northern grass frog, Rana pipiens. AAT is sensitive to both opioid and adrenergic agonist modulation. The present study introduces the novel use of mechanical and thermal stimulus behavioral assays in comparison with the established acetic acid test in studying nociception in frogs. We evaluated mechanical and thermal responses and their sensitivity to systemic morphine (MOR) or dexmedetomidine (DEX) administrations with comparison to AAT. MOR produced dose-related elevations of response thresholds in all three sensory tests, whereas DEX produced elevations in the thermal and AAT assays but had no effect on sensitivity to non-noxious mechanical stimuli. The results suggest a distinct separation of sensory modalities in the frog similar to that observed in mammals and indicate the usefulness of this amphibian model in further studies of nociception.
authors.affiliation: Department of Pharmacology and Physiology, Oklahoma State Univ. College of Osteopathic Medicine, Tulsa, 74107, USA.
authors.forename: S
authors.initials: S
authors.lastname: Willenbring
authors.forename: C W
authors.initials: CW
authors.lastname: Stevens
mesh_terms: D000085:Acetates; D019342:Acetic Acid; D018663:Adrenergic Agents / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004353:Drug Evaluation, Preclinical / Q000379:methods; D006361:Heating; D007093:Imidazoles / Q000494:pharmacology; D020926:Medetomidine; D009020:Morphine / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D010147:Pain Measurement / Q000187:drug effects* / Q000379:methods*; D011894:Rana pipiens / Q000502:physiology*; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds / Q000187:drug effects; D013314:Stress, Mechanical
chemical_list: D000085:Acetates; D018663:Adrenergic Agents; D007093:Imidazoles; D009294:Narcotics; D009020:Morphine; D020926:Medetomidine; D019342:Acetic Acid