5-HT potentiates GABA- and glycine-activated chloride currents on the same neurons in rat spinal cord.
The electrophysiological and pharmacological properties of GABA- and glycine (Gly)-induced responses were investigated in neurons acutely dissociated from the rat sacral dorsal commissural nucleus (SDCN) using the nystatin perforated patch recording configuration under voltage-clamp conditions. At a holding potential of -40 mV, the currents evoked by GABA and Gly increased in a sigmoidal fashion with increasing agonist concentration. The reversal potentials of I(GABA)and I(Gly) were close to the Cl- equilibrium potential. Bicuculline (BIC) and strychnine (STR) suppressed I(GABA) and I(Gly) in a concentration-dependent manner, although they have different affinities for GABA and Gly. 5-HT potentiated both I(GABA) and I(Gly) via intracellular protein kinase C on the same neurons. The results indicated that the acutely dissociated SDCN neurons responded to both exogenous GABA and Gly, which activated GABA(A) and STR-sensitive Gly receptors, respectively, and 5-HT may produce spinal antinociception through postsynaptic potentiation of I(GABA) and I(Gly) when they are coreleased; GABA and Gly may act as cotransmitters implicated in the control of spinal nociceptive signal processing in the mammalian spinal cord.
Wang
D S
DS
Department of Anatomy and K.K. Leung Brain Research Center, Fourth Military Medical University, Xi'an, People's Republic of China.
Xu
T L
TL
Li
J S
JS
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002273:Carcinogens / Q000494:pharmacology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D018756:GABA Antagonists / Q000494:pharmacology; D005998:Glycine / Q000378:metabolism* / Q000494:pharmacology; D018684:Glycine Agents / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012445:Sacrococcygeal Region; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013331:Strychnine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism* / Q000494:pharmacology
D002273:Carcinogens; D018118:Chloride Channels; D002712:Chlorides; D018756:GABA Antagonists; D018684:Glycine Agents; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D011493:Protein Kinase C; D013331:Strychnine; D013755:Tetradecanoylphorbol Acetate; D005998:Glycine; D001640:Bicuculline