Serotonin potentiates the response of neurons of the superficial laminae of the rat spinal dorsal horn to gamma-aminobutyric acid.
Employing the Nystatin-perforated whole-cell patch-clamp recording technique, the modulatory effects of serotonin (5-HT) on gamma-aminobutyric acid (GABA)-activated whole-cell currents were investigated in neurons acutely dissociated from the superficial laminae (laminae I and II) of the rat spinal dorsal horn. The results showed: (1) GABA acted on GABA(A) receptors and elicited inward Cl(-) currents (I(GABA)) at a holding potential (V(H)) of -40 mV; (2) 5-HT potentiated GABA-induced Cl(-) current without affecting the reversal potential of I(GABA) and the apparent affinity of GABA to its receptor; (3) alpha-methyl-5-HT, a selective agonist of 5-HT(2) receptor, mimicked the potentiation effect of 5-HT on I(GABA), whereas ketanserine, an antagonist of 5-HT(2) receptor, blocked the potentiation effect of 5-HT; (4) Chelerythrine, an inhibitor of protein kinase C, reduced the potentiation effect of 5-HT on I(GABA). The present results indicate: (1) The potentiation of 5-HT on I(GABA) is mediated by 5-HT(2) receptor and through a protein kinase-dependent transduction pathway; (2) The interactions between 5-HT and GABA might play an important role in the modulation of nociceptive information transmission at spinal cord level.
Li
H
H
Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, People's Republic of, Xi'an, China.
Lang
B
B
Kang
J F
JF
Li
Y Q
YQ
D000818:Animals; D002478:Cells, Cultured; D004347:Drug Interactions / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D020671:Posterior Horn Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000145:classification / Q000187:drug effects / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism* / Q000494:pharmacology*
D011985:Receptors, Serotonin; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D011493:Protein Kinase C