title: Differential actions of spinal analgesics on mono-versus polysynaptic Adelta-fibre-evoked field potentials in superficial spinal dorsal horn in vitro.
abstract: Processing of nociceptive information can be modulated at various levels in spinal cord that may range from changes of neurotransmitter release from primary afferent Adelta- or C-fibres to excitability changes of spinal interneurones or motoneurones. The site and mechanism of action of spinal analgesics has been assessed with a number of in vivo and in vitro methods with sometimes conflicting results. Here, we have used transverse spinal cord slices with attached dorsal roots to simultaneously record mono- and polysynaptic Adelta-fibre-evoked field potentials in superficial spinal dorsal horn. Two classical spinal analgesics, morphine and clonidine, and the metabotropic glutamate receptor agonist (IS,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD) differentially affected mono- and polysynaptic Adelta-fibre-evoked transmission in spinal dorsal horn. Polysynaptic responses were dose-dependently inhibited while the monosynaptic response remained unaffected. These results suggest that spinal analgesics may preferentially affect polysynaptic but not monosynaptic Adelta-fibre-evoked responses in superficial spinal dorsal horn.
authors.affiliation: Institute of Physiology and Pathophysiology, Heidelberg University, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany.
authors.forename: Ruth
authors.initials: R
authors.lastname: Ruscheweyh
authors.forename: Jürgen
authors.initials: J
authors.lastname: Sandkühler
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000700:Analgesics / Q000008:administration & dosage* / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D003515:Cycloleucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007278:Injections, Spinal; D009020:Morphine / Q000494:pharmacology; D009413:Nerve Fibers, Myelinated / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists; D017981:Receptors, Neurotransmitter / Q000037:antagonists & inhibitors; D013116:Spinal Cord / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects*
chemical_list: D000700:Analgesics; D000701:Analgesics, Opioid; D018094:Receptors, Metabotropic Glutamate; D017981:Receptors, Neurotransmitter; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; D009020:Morphine; D003000:Clonidine