Serotonergic modulation of neurotransmission in the rat subicular cortex in vitro: a role for 5-HT1B receptors.
We have studied the effect of serotonin on synaptic transmission in rat hippocampal subiculum slices. Electrical stimulation of the alveus induced a field potential in the subiculum. The non-NMDA glutamate receptor antagonist, NBQX (3 x 10(-6) mol/l) suppressed the response by 78%, indicating that the signal involves glutamatergic neurons. Application of serotonin suppressed (EC50 = 3.6 x 10(-6) mol/l) the amplitude of the evoked potentials in a reversible, concentration-dependent manner. The responses to 5-HT were not altered after pretreatment with the 5-HT uptake blocker, fluvoxamine (10(-5) mol/l) or a combination of the MAO inhibitor pargyline (10(-5) mol/l) and ascorbic acid (10(-4) mol/l). The responses to 5-HT were also unaffected by pretreatment with the 5-HT1A selective antagonist NAN-190 (10(-6) mol/l), the 5-HT2A antagonist ketanserin (10(-6) mol/l) or the 5-HT3/5-HT4 antagonist ICS 205-930 (10(-6) mol/l). The 5-HT1B selective agonist CP 93,129 mimicked the effects of serotonin, but was more potent (EC50 4.1 x 10(-7) mol/l). The 5-HT1B receptor antagonist, (+/-)21-009 (3 x 10(-7) mol/l), antagonized the response to 5-HT and CP 93,129 with a pKB value of 7.1 and 7.2, respectively. These results suggest that the effect of 5-HT in the rat subiculum is mediated by 5-HT1B receptors.
Boeijinga
P H
PH
CNS Department, Sandoz Pharma Ltd., Basle, Switzerland.
Boddeke
H W
HW
D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D005971:Glutamates / Q000502:physiology; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
D005971:Glutamates; D008996:Monoamine Oxidase Inhibitors; D016194:Receptors, N-Methyl-D-Aspartate; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin