Serotonin receptor activation reduces calcium current in an acutely dissociated adult central neuron.
The release of serotonin (5-HT) from the terminals of serotonergic (raphe) neurons is under inhibitory feed-back control. 5-HT, acting on raphe cell body autoreceptors, also mediates inhibitory postsynaptic potentials as a result of release from collaterals from neighboring raphe neurons. This may involve a ligand (5-HT)-gated increase in the membrane potassium conductance, leading to a decrease in action potential frequency, which could indirectly reduce calcium influx into nerve terminals. In this report we demonstrate that 5-HT can also directly reduce calcium influx at potentials including and bracketing the peak of calcium current activation. Using acutely isolated, patch-clamped dorsal raphe neurons, we found that low concentrations of 5-HT and the 5-HT1A-selective agonist 8-OH-DPAT reversibly decrease whole-cell calcium current. This effect is antagonized by the putative 5-HT1A-selective antagonist NAN 190. Hence, the inhibition of calcium current may serve a physiological role in these cells and elsewhere in the brain.
Penington
N J
NJ
Department of Pharmacology, University of Edinburgh Medical School, Scotland.
Kelly
J S
JS
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000493:pharmacokinetics / Q000502:physiology*; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D004553:Electric Conductivity / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
D010879:Piperazines; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D013764:Tetrahydronaphthalenes; C058895:1-(2-methoxyphenyl)-4-(4-(2-phthalimido)butyl)piperazine; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D002118:Calcium