title: Effects of serotonin on hilar neurons and granule cell inhibition in the guinea pig hippocampal slice.
abstract: Intracellular recordings in guinea pig hippocampal slices were used to study the effects of serotonin (5-HT) on presumed inhibitory hilar neurons and on postsynaptic inhibition of granule cells. 5-HT applied by the bath hyperpolarized only 50% of the hilar neurons tested but all CA3 neurons and granule cells, presumably by activating a K-conductance. The bath application of 4-aminopyridine (4-AP, 50 microM) induced burst discharge activity in hilar neurons and giant inhibitory postsynaptic potentials (IPSPs) in granule cells consisting of a Cl- and K-component. 5-HT (5-10 microM) reversibly blocked the K-component of giant IPSPs in granule cells, but not their Cl-component. In the majority of hilar neurons 5-HT increased the frequency of 4-AP induced burst discharges even when hilar neurons were hyperpolarized. Only in a few hilar neurons 5-HT blocked 4-AP induced burst discharges. We conclude that the changes in burst discharge pattern of hilar neurons correspond with the differential effect of 5-HT on Cl- and K-mediated inhibition of granule cells.
authors.affiliation: I. Physiologisches Institut, Universität Heidelberg, FRG.
authors.forename: B M
authors.initials: BM
authors.lastname: Ghadimi
authors.forename: W
authors.initials: W
authors.lastname: Jarolimek
authors.forename: U
authors.initials: U
authors.lastname: Misgeld
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects; D018118:Chloride Channels / Q000187:drug effects; D004566:Electrodes; D005071:Evoked Potentials / Q000187:drug effects; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009474:Neurons / Q000187:drug effects*; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D018079:Receptors, GABA / Q000187:drug effects; D017661:Receptors, Presynaptic / Q000187:drug effects; D012701:Serotonin / Q000494:pharmacology*; D013569:Synapses / Q000187:drug effects
chemical_list: D018118:Chloride Channels; D015221:Potassium Channels; D018079:Receptors, GABA; D017661:Receptors, Presynaptic; D012701:Serotonin; D015761:4-Aminopyridine; D001418:Baclofen