Serotonin and 8-OH-DPAT reduce excitatory transmission in rat hippocampal area CA1 via reduction in presumed presynaptic Ca2+ entry.
The effect of 5-HT and its 1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) on excitatory transmission in CA1 pyramidal cells was studied. Using concentrations of 5-HT within a range of 10-50 microM we observed no change in excitatory postsynaptic potentials (EPSPs) in CA1 cells evoked by Schaffer collateral stimulation. However, at higher concentrations, > or = 100 microM, 5-HT caused a significant decrease (30-40%) in EPSP/Cs, an effect that was also mimicked by 50 microM 8-OH-DPAT. A presumed presynaptic Ca2+ entry was measured in stratum radiatum following repetitive stimulation of the Schaffer collaterals with all excitatory synaptic transmission blocked. Both 5-HT and 8-OH-DPAT reduced this Ca2+ entry. These results suggest that 5-HT acts at presynaptic 5-HT1A receptors to reduce Ca2+ entry and thereby glutamatergic synaptic transmission.
Schmitz
D
D
Department of Neurophysiology, Humboldt University Berlin, Germany.
Empson
R M
RM
Heinemann
U
U
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003864:Depression, Chemical; D004558:Electric Stimulation; D005260:Female; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017661:Receptors, Presynaptic / Q000187:drug effects / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects*
D017661:Receptors, Presynaptic; D017366:Serotonin Receptor Agonists; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D002118:Calcium