title: Some experimental pain indices and their applications in the study of analgesic mechanisms.
abstract: This communication presents some insights into the controversies and complications in experimental pain research using laboratory animals. In particular, I have singled out two experimental pain indices that are used in my laboratory for a decade, viz, dental pain model and hot-plate algesiometric assay for discussion. Using these two models, my colleagues and I have identified that morphine may promote analgesia by enlisting synergistic actions from the central cholinergic and dopaminergic systems, in a process that involves shifting of balance between various neurotransmitter systems. We confirmed the medullary nucleus reticularis gigantocellularis as a site for clonidine- and morphine-induced and stimulation-produced antinociception. Finally, a progressive increase in pain sensitivity and a gradual reduction in the analgesic potency of morphine and clonidine are unveiled in aging rats.
mesh_terms: D000698:Analgesia; D000818:Animals; D001696:Biomechanical Phenomena; D003000:Clonidine / Q000627:therapeutic use; D003782:Dental Pulp / Q000502:physiology; D004558:Electric Stimulation; D005071:Evoked Potentials; D006358:Hot Temperature; D007568:Jaw / Q000502:physiology; D008526:Medulla Oblongata / Q000502:physiology; D009020:Morphine / Q000627:therapeutic use; D010146:Pain / Q000188:drug therapy / Q000502:physiology*; D011930:Reaction Time; D012018:Reflex
chemical_list: D009020:Morphine; D003000:Clonidine