Reduction of glycine receptor-mediated miniature inhibitory postsynaptic currents in rat spinal lamina I neurons after peripheral inflammation.
Peripheral inflammation may induce long-lasting sensitization in the central nociceptive system. Neurons in lamina I of the spinal dorsal horn play a pivotal role in the integration and relay of pain-related information. In rats we studied whether changes in passive and active membrane properties and/or alteration of glycine receptor-mediated inhibitory control of spinal lamina I neurons may contribute to central sensitization in a model of peripheral long-lasting inflammation (complete Freund's adjuvant, hindpaw). Spontaneously occurring glycine receptor-mediated miniature inhibitory postsynaptic currents (GlyR-mediated mIPSCs) were recorded in lumbar spinal lamina I neurons. Miniature IPSC rise, decay kinetics and mean GlyR-mediated mIPSC amplitude were not affected by peripheral inflammation. The mean frequency of GlyR-mediated mIPSCs of lamina I neurons ipsilateral to the inflamed hindpaw was, however, significantly reduced by peripheral inflammation when compared with neurons from noninflamed animals. Principal passive and active membrane properties and firing patterns of spinal lamina I neurons were not changed by inflammation. These results indicate that long-lasting peripheral inflammation leads to a reduced glycinergic inhibitory control of spinal lamina I neurons by a presynaptic mechanism.
Müller
F
F
Institute of Physiology and Pathophysiology, Heidelberg University, D-69120 Heidelberg, Germany.
Heinke
B
B
Sandkühler
J
J
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001640:Bicuculline / Q000494:pharmacology; D004347:Drug Interactions; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D005260:Female; D005620:Freund's Adjuvant; D018756:GABA Antagonists / Q000494:pharmacology; D018684:Glycine Agents / Q000494:pharmacology; D066298:In Vitro Techniques; D007249:Inflammation / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D018009:Receptors, Glycine / Q000187:drug effects / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology*; D013331:Strychnine / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D014633:Valine / Q000031:analogs & derivatives* / Q000494:pharmacology
D000779:Anesthetics, Local; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D018684:Glycine Agents; D018009:Receptors, Glycine; D013779:Tetrodotoxin; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; C056639:2-amino-5-phosphopentanoic acid; D005620:Freund's Adjuvant; D013331:Strychnine; D014633:Valine; D001640:Bicuculline