Differential effects of the serotonin receptors on cultured rat cerebral cortical neurons.
Effects of serotonin (5-HT) on cerebral cortical neurons were examined by patch clamp techniques. 5-HT produced a variety of responses such as outward (19/73 patches/neurons), slow inward (15/73 patches/neurons), fast inward (8/73 patches/neurons), and mixed currents (initially fast inward deflection followed by an outward response: 2.73 patches/neurons), with a latency of 12 sec, 15 sec, 0 sec, and 0 sec respectively, at a holding potential of -60 mV in whole-cell patches. The fast inward currents were again evoked by a selective 5-HT3 receptor agonist, 1-(m-chlorophenyl)-biguanide hydrochloride (CPBG). In the cell-attached patch clamp configuration, 5-HT inside the patch pipette elicited single channel currents with slope conductances of 42 pS and 132 pS (4/42 patches/neurons). CPBG inside the patch pipette evoked inward single channel currents with a lower slope conductance of 41 pS (3/23 patches/neurons). In contrast, application of 5-HT or a 5-HT2 receptor agonist, alpha-methyl-5-hydroxytryptamine-maleate, outside the patch pipette induced outward single channel currents with a major slope conductance of 140 pS (8/30 patches/neurons) or 135 pS (6/20 patches neurons), respectively. These results indicate that the outward and fast inward currents may be mediated respectively by the 5-HT2 receptor, which is coupled to a G-protein, and by the 5-HT3 receptor, which contains the non-selective cation channel, and that the mixed type may be caused by both the 5-HT2 and 5-HT3 receptors.
Matsuoka
T
T
Department of Public Health, Kobe University School of Medicine, Japan.
Nishizaki
T
T
Ikeuchi
Y
Y
Okada
Y
Y
Sumino
K
K
D000818:Animals; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology / Q000502:physiology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D015398:Signal Transduction
D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D012701:Serotonin; D019204:GTP-Binding Proteins