title: Excitatory effect of serotonin on pacemaker neurons in spinal cord cell culture.
abstract: Intracellular recordings were made from fetal mouse spinal cord neurons in primary culture. One type of neuron, with large somata (40-50 microns diameter) and thick neurites exhibited endogenous bursting or beating pacemaker electrical activity. Noradrenaline depolarized this type of neuron by decreasing an M-like conductance. Micropressure application of serotonin (10(-5) M in the delivery pipette) onto the surface of pacemaker neurons evoked a depolarization of the membrane potential in a dose-dependent manner with an increased input resistance. No such response was observed with other types of spinal cord neurons in culture. The response to serotonin was partially voltage-dependent. The serotonin-induced depolarization reversed at holding potential close to -100 mV. However, the input resistance variation evoked by serotonin increased exponentially when membrane potential was depolarized. The reversal potential was modified by increasing extracellular K+ concentration and it was unaltered by increasing the intracellular Cl- concentration. The decrease in K+ conductance induced by serotonin was not suppressed by the application of tetraethylammonium (50 mM) or 4-aminopyridine (10 mM). Furthermore, application of Ba2+ (6 mM) or Cd2+ (0.1 mM) had no effect on this response, suggesting that the depolarization evoked by serotonin application was not calcium-dependent. The serotonin evoked increase in input resistance was mediated by activation of a 5-HT1A-like receptor site. Spiperone, a 5-HT1A antagonist reversibly blocked the response. Methiothepin, a 5-HT1-5-HT2 antagonist (10(-3) M); cocaine, a 5-HT3 antagonist (10(-3) M); ketanserin, a 5-HT2 antagonist (10(-3) M); and prazosin, an alpha 1 antagonist (10(-3) M) had no effect.(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Unité de neurobiologie des comportements, INSERM U176, Domaine de Carreire, Bordeaux, France.
authors: P
authors: P
authors: Legendre
authors: A
authors: A
authors: Guzman
authors: B
authors: B
authors: Dupouy
authors: J D
authors: JD
authors: Vincent
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004553:Electric Conductivity; D004594:Electrophysiology; D007473:Ion Channels / Q000502:physiology; D007477:Ions; D009474:Neurons / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D010507:Periodicity; D012701:Serotonin / Q000494:pharmacology*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*
chemical_list: D007473:Ion Channels; D007477:Ions; D012701:Serotonin; D009638:Norepinephrine